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DIY: Troubleshooting S.A.S. and How to Replace the Famous Fuse # 107!

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#1 · (Edited)
DIY: Troubleshooting S.A.S. and How to Replace the Famous Fuse # 107!

- I have emission codes P1421 and P1423 (S.A.S. codes saying not enough air is injected into the exhaust during cold start), which is very common for car this age 10y/100K miles.

- In order to understand the S.A.S. system, you need to read the attached pdf on S.A.S.:
---> In brief, when engine is cold, the Air Pump injects additional air into the exhaust to reduce pollutants.
---> The Air Pump is designed for high output but short run, so it injects air for anywhere between 2.5 seconds and 105 seconds or so, depending on engine temp.

- These are PNs for 1998 528i, listed only for reference, later years are slightly different. This is taken from www.realoem.com:
* Electrical Valve; PN 11747537612 (about $45)
* Air Valve: PN 11727540467 (about $110)
* Air Valve Gasket; PN 11727505259 (about $4)
* Pierburg Air Pump; PN 11721427911 (about $250)
* Air Pump Relay (K6304): schema is 85-86 and 30-87a-87, PN 12631742690 (about $8)
* Fuse #107: 50A Special Fuse: BMW PN 61138365901 ($4.00); Napa PN 782-1144 ($4.00). The BMW Fuse is covered in black and you cannot check it with your naked eyes (need Voltmeter or Ohmmeter to check). The Napa Fuse is see-through: within a glance you can see the fuse is good or not. I prefer the Napa Fuse. See pic:



- To be sure the Air Pump is bad, remove it and apply 12V to the 2 pins, if it does not run, either the bearing is seized or the motor is gone. You have 2 options:
1. New Pierburg Air Pump is about $250.
2. Rebuild the Air Pump using a standard bearing SKF 626 (ID = 6mm; OD = 19mm ; W = 6mm). Complete Air Pump Rebuild Info is here:
http://www.bimmerfest.com/forums/showthread.php?t=402816

This is the sequence of S.A.S. system when you start the car cold:
- ECU sends signal to the Electrical Valve (this Valve sits under the Intake Manifold), which in turn opens a small channel to allow vacuum from the Intake Manifold to be applied to the Air Valve (which sits on the Exhaust Manifold)
- At the same time, signal is sent to the Relay to close the 85-86 "primary" circuit, which in turn closes the 30-87 "secondary circuit". In general, the "secondary circuit" in most Bosch relay circuits controls the high current flow.
- In the case of the S.A.S. Air Pump, the 30-87 circuit is controlled by the Fuse # 107, which itself is under the passenger's seat, thanks to the BMW engineers who designed this car with beer and bratwurst!!! In any other car, replacing this fuse is not hard because it is usually located under the hood. In the E39, Fuse 107 is a bit tricky to get too, but not too bad.



SOME DIAGNOSTIC PROCEDURES:

- Check the small Vacuum line leading to Air Valve, it is usually cracked with time/heat.

- To check Electrical Valve, during cold start, Disconnect (D/C) the small vacuum hose and feel for vacuum, there should be some vacuum from the small hose b/c the Electrical Valve opens the port to allow vacuum from the Intake to the small hose. Now re-connect the small hose.

- Air Valve and Gasket testing: Disconnect (D/C) the large hose to Air Valve, start engine during cold, after a few seconds there should be vacuum at the Air Valve (feel with your palm of your hand), if not either the Air Valve itself or the Electrical Valve is bad.

- Air Pump Testing: At the same time as above, the Air Pump is activated, so you should feel air blowing out of the large hose that you just disconnected above, if not, then the culprits are:
a. The Fuse #107 is blown. When this happens, usually something else is bad (like Bad Air Valve allowing water from exhaust to enter the Air Pump, destroying the bearing is blown ---> the Air Pump is dead. If the Air Pump is shorted electrically, the new fuse will be blown again. So if the fuse is blown, investigate it further. In my case the Air Pump was seized.
b. S.A.S. relay is bad (rare).

- Before getting to Fuse #107 under the passenger seat, check the S.A.S. Relay and its connector first!!! The Main Fuse Box is under the passenger side Cabin Filter. Remove the Passenger Cabin Filter Housing.

- Using Allen keys, open the Plastic Cover and you will see the setup below with all the main relays and some fuses here. To check the S.A.S. Relay, remove it & check for continuity between 30 and 87a, it should be 0 Ohm. Now apply 12V to 85 and 86, 30 and 87 (not 87a) is now connected.

- Now check the Relay Connector, take note of the relay pinout, then copy it to a piece of paper because when reading relay upside down, it is very very easy to get all the connector terminals mixed up! By copying the terminals numbers (basically mirror image of the relay) to a piece of paper, you eliminate error! Over the years, I have learned this the hard way, so trust me with this copying to a piece of paper. There should be 12V to #30 terminal all the time. See pic:



PROCEDURE TO REPLACE FUSE #107 UNDER PASSENGER SEAT:
Now that you have determined that there is no power to terminal #30 in the Relay Connector itself, time to check and replace the 50A Special Fuse.

1. The Trim piece: using flat screw driver pry it up, it is held by 3 White clips.



2. The Seat is held by four (4) Torx #50 bolts, remove them but no need to take the seat out of the car.



3. The Vertical Trim piece: undo the bottom part only to allow the carpet to be folded back.

4. Note how the carpet fits (the front carpet piece slides under the rear piece).

5. Fold the carpet back and place a brick on it to hold it there to free your hand. You will see a Styrofoam insulation piece. In order to remove the Styrofoam in its entirety, you have to remove the plastic tunnel (HVAC Tunnel), which is more work! I bypassed this step: I leave the plastic tunnel alone but break the styrofoam at where it meets the plastic tunnel b/c it is a only a piece of insulation, nothing fancy about it.

- Use a short piece of wood to prop the seat up about 12".



6. Now you see the Electrical Distribution Center, remove the white plastic covers to expose the Red (+) connections. Ground (Brown Cables) is just to the Left of this distribution box.

7. Fuse Block has a total of 8 fuses. Fuse #107 is on the far Left. See picture:



8. To test the Fuse, use a Voltmeter (not Ohmmeter for now).

9. Note the Large Red Feed Cable side, it feeds power to the electrical block where it branches out. So probing on that side must read 12V or so. Now probe the other side of the fuse, it should read 12V as well, if it reads 0 volts, the fuse is bad.

10. To replace the 50A Fuse, it is held by 8-mm nuts and square washer. Use a small hook to hook it out. Remove the fuse and confirm that it is bad with an Ohmmeter: when a fuse is bad it reads infinity Ohms (open circuit).
* CAUTION: this circuit is always "hot" with 12V, even with key out of ignition! If you are not comfortable working with "hot" wire, then disconnect the red cable from the trunk battery. I did this whole thing with the battery connected, just pay attention not to touch any ground while removing the 8-mm and 10-mm nuts.



11. The medium-sized red cable feeding separate electrical items in the car is held by a single 10-mm nut.

12. NOTE the torque for these nuts, basically tight and snug a bit:
* 8-mm nut: 8 Nm
* 10-mm nut: 15 Nm

13. Now you need to address the Air Pump. Either buy a new Air Pump or rebuild it, otherwise this fuse will blow again! Info for Air Pump is mentioned above.

That is all boys and girls, not too difficult if you know what you are doing!
 

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#3 ·
Another cn90 DIY bookmarked! :thumbup: This DIY is a great complement to the simple replacement of the air pump and valve. If your fuse is the culprit, this DIY will save you big $$$ over replacing the air pump. My previous e39 spit out air pumps annually. This one has been solid since I got it :dunno: Very strange...
 
#4 ·
You guys will be pleasantly surprised.

So I ordered a brand new pump which will not arrive until next week. In the mean time, I reset the CEL light, removed the Air Pump from the car and guess what, for the last few days....no codes at all!
This is because when the Air Valve (which sits on top of the exhaust manifold) is activated during cold start, it acts like a vacuum valve sucking in air. The Air Pump helps push more air in.

When an Air Pump fails, it acts like a road block to air flow because it stops running.

However, removing the Air Pump allows the Air Valve to suck in air as it wishes, which accomplishes the same job of reducing pollutants. It will be a bit noisy during the cold start, then it will quiet down.

So, if you are so tight with budget for a new Air Pump:

1. Remove the Air Pump

2. Reset the OBD-II Check Engine Light.

3. Cap the open end of the hose with home window screen (the same stuff sold at hardware store to repair broken home window screen, which is the screen to keep bugs from getting inside the house). It is a few dollars at hardware store. Then duct tape and gently zip tie it. This is to prevent leaves/debris from getting into the hose.

Try this and report back.

I was pleasantly surprised when I discovered this "Eureka" while waiting for the new Air Pump to arrive. "Look Ma, no code"....:)
Anyway I already ordered a new Air Pump, so the Air Pump will go in.

The SAS system sounds great in theory but what a piece of junk (to make tree hugger happy for 1 minute!).
 
#8 · (Edited)
:)

9 times out of 10 a failed pump is due to a failed valve at the exhaust manifold.

problem is that when the valve fails it does not "suck in air" it lets exhaust gases out. Listen for your new exhaust leak when the engine is cold, and look at the soot that will develop wherever your open hose ends as signs. Why do you suppose an air pump is needed? if it drew in air by itself they would have designed it that way. All you are doing is blowing exhaust under the hood on cold start, which is not good to recommend considering your cabin filters are also in that area. If they are perfectly sealed you may not notice, but an aging e39s cabin filter system is usually anything but air tight. Sorry but I can't agree with that even as a temp fix. Carbon monoxide is lethal. This temp fix relies solely on you having a good valve at the exhaust, which is not the case more often than not. If the one way valve is working you may get away with it.

The other thing to mention here is that if your car is eating these pumps annually or more change the valve! They get full of carbon and fail, which ruins it and lets exhaust out into your pump, or if you have unplugged your pump it will just waft under the hood and car. One of my 528i cars has had 3 of these pumps fail in the past. The other is on the OEM pump from 1998. Guess which one has a good exhaust valve in it?

Your diagnosis and other info is spot on and will be very useful for others, but I think the best bet if you need a new pump and valve is to leave the old parts alone until you have replacements. I'd rather see a CEL for a couple days until parts come in than risk breathing in poisonous gases.
 
#10 · (Edited)
:)...problem is that when the valve fails it does not "suck in air" it lets exhaust gases out. Listen for your new exhaust leak when the engine is cold, and look at the soot that will develop wherever your open hose ends as signs. Why do you suppose an air pump is needed? if it drew in air by itself they would have designed it that way. All you are doing is blowing exhaust under the hood on cold start, which is not good to recommend considering your cabin filters are also in that area. If they are perfectly sealed you may not notice, but an aging e39s cabin filter system is usually anything but air tight. Sorry but I can't agree with that even as a temp fix. Carbon monoxide is lethal. This temp fix relies solely on you having a good valve at the exhaust, which is not the case more often than not. If the one way valve is working you may get away with it.

The other thing to mention here is that if your car is eating these pumps annually or more change the valve! They get full of carbon and fail, which ruins it and lets exhaust out into your pump, or if you have unplugged your pump it will just waft under the hood and car. One of my 528i cars has had 3 of these pumps fail in the past. The other is on the OEM pump from 1998. Guess which one has a good exhaust valve in it?
Hi Mark,

I am not advocating throwing away the Air Pump. I am simply reporting what I observe b/c I find it interesting.

Actually my Air Valve is brand new. I understand that a Bad air valve allows exhaust air/moisture to enter the Air Pump and destroy the Air Pump. But in a normal Air Valve, it sucks in air during cold start (disconnect the hose at the air valve; run the engine during cold start, try it with the palm of your hand and you will see it sucks in air; then re-connect the hose).

For a long time, I always thought the Air Valve simply opens a gate, then the Air Pump blows air into the exhaust manifold, then the O2 sensors registers a change in reading, and the ECU is happy about the readings, no codes are reported.
Well, I checked and during cold start, the Air Valve sucked in air!

* My observation:
1. During cold start, it has similar noise like as if the Air Pump is running in a normal car; nothing unusual.
2. Then roughly 1 minute later, all quiet like the way it has been the last 4 years. Checked the hose: no vacuum b/c the Air Valve is shut now.

Re: carbon monoxide etc.
My disconnect point is not under the hood, it is in the wheel well, where the blue arrows area, just behind the fog light area. So in the event the Air Valve fails (if you remove the Air Pump), exhaust gas will enter the wheel well area as shown; and in that case of Air Valve failure (the Air Valve lasts about 80-100K), it will be noisy, and you will know about it and change to a new Air Valve. No C.O. danger to worry about.

If my theory proves to be correct, then one can always add a short hose to route it under the bumper, just in the event of Air Valve failure, exhaust gas is pumped under the bumper. I think this whole SAS thingy is over-engineered.

 
#11 ·
trust me, I am not fond of the system myself, having went through a couple pumps before I realized that valve was shot years back. I have run my personal car without one for some time, I keep wanting to fix it but other things take priority. Even with a work discount the parts are $.

One interesting tidbit I will share from my experiences with my car, 98 528i. Recently reprogrammed the entire car's modules after a manual transmission swap so that the various error lights would not be on anymore and I could pass smog. I do not have the air pump plugged in electrically at the moment, nor was it when I programmed the car. I was expecting the same old SAP codes to register a day or two after flashing the DME, but it never came back. I have put hundreds of miles on it since and still no light. I wonder if by leaving it unplugged when I reprogrammed the car's modules if it may have caused the car to no longer look for the thing. My other thought is that the software I used on my engine computer may have been an updated version that does not trip the light for SAP errors. (flashed DME with progman 32) Either way a trouble code scan of the DME shows "no errors!" Works for me. :)
 
#16 ·
My other thought is that the software I used on my engine computer may have been an updated version that does not trip the light for SAP errors. (flashed DME with progman 32) Either way a trouble code scan of the DME shows "no errors!" Works for me. :)
Interesting. Out of curiosity are you tested for cold start emissions in parts of the US? Euro E39s completely omit this system.
 
#14 ·
1. Attach picture to the thread.
2. Move mouse over to the pic and Right click Properties.

You will see it says for example:
"http://www.bimmerfest.com/forums/attachment.php?attachmentid=203675"

(In new post with new pics, it usually says
"http://www.bimmerfest.com/forums/attachment.php?attachmentid=203675........blahblahblah"
but all you need is the attachmentid #, so delete the blahblahblah after the attachmentid number).

3. Then Click on "Insert Image" and enter the link wherever you want it.
 
#15 ·
@ cn90,
Could you review and edit your most excellent post? I believe there is a typo in the WDS Wiring Diagram System print you have displayed. The Secondary air pump relay in the diagram has the #30 terminal and the #87 terminal reversed. I just triple checked this on a '01 525i and the #87 is always hot and the #30 has continuity to the pump.
This means your drawing of the K6304 Connector for the air pump relay will also need editing. We wouldn't want a noob to think that his BMW has crossed it's Plasma streams somewhere and undergone Total Protonic Reversal. :eeps:
 
#17 ·
The above diagram is CORRECT.

I made the same mistake because I was looking at the RELAY instead of the CONNECTOR.
It can be confusing if you are not careful!
You need to get the CONNECTOR pins properly labeled!!!

Best is to get a piece of paper and place the RELAY on top on the paper and trace the numbering system like 30, 85, 86, and 87, now use this piece of paper for the CONNECTOR numbering system.
 
#18 · (Edited)
It is easy to get the 30 and 85 terminal mentally reversed but not the 87 and 86. The labeling on the diagram you made of the CONNECTOR for the relay is correct but the image of the WDS Wiring Diagram System does not conform to the testing I did.

When testing this '01 525i I have in the shop I find that the 87 slot on the CONNECTOR is definitely hot all the time while the 30 slot definitely shows continuity to the plug for the pump. (testing also shows that 86 becomes hot as it should when I turn the ignition on)

The image (and your description) of the WDS Wiring Diagram System suggests that the 30 slot in the CONNECTOR should be hot all the time and the 87 should lead to the pump. This does not conform to my probe testing

Note:
One of the reasons I had to be extra careful about this is that the physical layout of the vast majority of relays I have seen in my 20 years as a mechanic specializing in electrical trouble shooting (my major in collage was Electrical Engineering) has the 30 and 86 terminals reversed from your drawing. Typically 85 and 86 are the low current actuating coil terminals and they stand opposite and parallel each other on the relay while 30 and 87/87a are the high current load bearing pair of terminals that are opposite and perpendicular to each other on the relay. This Air Pump relay changes that conventional configuration to the layout you have correctly described in your drawing of the CONNECTOR.

The image of the WDS Wiring Diagram System is technically set up correctly. 30 SHOULD be hot all the time as per German wiring convention and the motor terminal 87 is properly switched between hot 30 and ground 87a to dump the back EMF and park the motor. Unfortunately that does not conform to how the car is actually built and the screwball (in my experience) layout of this Air Pump relay and its connector.

*IMPORTANT NOTE* Please read the reply I made right after this post.
~~~~~~~~~~~~~__/)_~~~~~~~~~~~~~~
 
#19 ·
@cn90
Now that I think about this you are right in your descriptions and diagrams. I believe this 525i was wired incorrectly from the factory so I am going to swap the wires going into the 30 and 87 slots in the CONNECTOR. 30 SHOULD be the hot wire while 87 SHOULD be the pump wire.

The car being wired improperly as it has been would work OK but it would not give the back EMF in the motor anywhere to go when switched off which would be hard on the motor and hard on the relay. It would also confuse the poop out of anyone who is trying to probe and diagnose this wiring. :confused:
 
#21 ·
Never try to replace fuse #107 with the battery still connected unless you like resetting air bag faults.

The Pierburg for an Audi A4 was just bought used at a salvage yard for $17 and mounts in the same mount as ours. A new air pump for the A4 can be bought for $100 on Amazon. Why buy the BMW pump?

Disconnecting the SAP will not act like a SIM-Sorry. Been there, done all this......

Good news and good work CN90, but nothing new here.
 
#23 ·
Is my problem in the relay?

Good day,

First of all, let me thank the editor of the DYI for an outstanding job. It has helped me a lot when I replaced the secondary air pump on my 2000 528i.

That being said, it is still not working. Here is what I have done.

1- The BWM dealer told me my pump was dead and needed to be replaced. So I replaced it with a new one. I also replace the air valve, and hose and the hose.
2- Since doing this did not help, I replaced fuse #107 and tested it. The new one works fine. It gets 12v and there is continuity through it.
3- Since my air pump was still not working, I had a look at the relay and measured voltage and resistance. Here are my findings:

- 87 was hot (12v) all the time
- 30 is not hot.
- 85 only had .1v with the key in position II
- resistance b/w 85-86 was 78 ohms (not sure if this is important).

So, if I understood your post correctly, there is something wrong with the connector. Or maybe it's before the connector.

Can anyone help?

Many thanks,

Max
 
#26 ·
...
3- Since my air pump was still not working, I had a look at the relay and measured voltage and resistance. Here are my findings:

- 87 was hot (12v) all the time
- 30 is not hot.
- 85 only had .1v with the key in position II
- resistance b/w 85-86 was 78 ohms (not sure if this is important).
Max,

Wait for "billj3cub" to get back on this issue.

I find it hard to believe billj3cub's car wired backward, if so, it would have given problem the last 10 years or so.

Make sure you remove the SAS Relay and look at the pins and make a diagram on a piece of paper so you know exactly the locations of 30, 85, 86, 87 etc. on the CONNECTOR.

Then search the internet for the wiring diagram for your model year. What is your model/year?

Wiring Info is here:

http://spaghetticoder.org/bmw/wds/

http://www.bmw-planet.com/diagrams/release/en/
 
#24 ·
Your #86 terminal on the connector should be hot (12v) when you turn the key on. If not, then you need to check the F31 fuse (where is that located?).

You can test the air pump by putting a jumper wire between 87 and 30 to see if the pump runs.

You have the same 87-hot (from fuse 107) and 30-cold (to pump) apparent backwards connector wiring that I believe I have on this '01 525i. My customer has the car right now. Give me a week and I will get the car back to install a good pump I got at a wreaking yard for $125 (his original pump was all melted down inside and not rebuild-able). I will triple check everything, swap the wires so #30 in the connector is hot and #87 in the connector runs to the pump then report back on how it all turned out.
 
#28 · (Edited)
Ok, I pulled my Bentley out as it has been a while since my SAP went south. Mine filled with condensation, froze in the winter causing the rotor to be "locked". The caused excessive current drain on fuse 107 blowing it. So, I replaced fuse 107, the relay (salmon colored), pump, hoses, and valve. The whole she-bang.

First, contact 87 should ONLY be hot for about 90 seconds after turning the key on AND STARTING CAR. If you waited with car running and 87 stayed hot, then your relay is toast as it is stuck closed. This would cook your pump as they are only made to run a MAX. of about 4 minutes before they will burn up. You need to make sure when you test for 12 VDC at 87 that you started the car and kept your meter on relay contact 87 for at least a few minutes. At least you know fuse 107 is good. If contact 87 is hot verify you have 12 VDC at the pump as well. You really need to just pull the pump out and using a car battery put a known BIG 12 volts to the pump and see if it hums and or turns. If it does not even hum, it is toast. If it hums, but acts like it is locked, drill out rivets and take apart and see if you can clean it up and un-freeze it. Look for an Audi Pierburg pump and save about $200 bucks over a BMW pump. Audi pump is just as good. Search for the post about replacing BMW pump with Audi pump. Direct fit except connector pigtail from your BMW must be changed to mate with the Audi pump. No big deal. You can even just use stake-on pins. Just observe polarity.

Pins 85 & 86 are the relay coil
Pin 30 is constant 12VDC from fuse 107
pin 87 goes hot when DME calls for pump to run
pin 87a is irrelevent for our purposes.
 
#29 · (Edited)
http://bimmerboard.com/forums/posts/792253

it has been a while since my SAP went south.
I went to the VERY best of E39 Links to see if this DIY is listed and realized we didn't have a concise paragraph about the SAP, SAS, and fuse #107.

Here's what /secondary(F3) nets us, from top to bottom:

Doing just /SAS(F3) nets these additional best links:

Next, I'll open them all up, read 'em, cull out duplicates, and put them into a keyword-rich coherent sentence.

- Where is the secondary air pump (1) & how to diagnose a secondary air system failure (1) & what are the most common two failure modes (1) & a DIY to perform SAS troubleshooting with the infamous fuse #107 (1) (2) & what to do when the SAP (1) clogs or freezes (1) or the diverter valve clogs (1), taking out the S.A.S. (1) (2) (3) (4) (5) (6) (7) & a S.A.P. replacement DIY (1) & a Pierburg air pump maintenance (1) & rebuild DIY (1) (2) & well thought out SAS/SAP simulation testing (1) & repair strategies (1).
 
#30 ·
SAP failure-Too long as usual :-(

Hi BLUE!

You know the post is valuable when you volunteer to pull it all together! Not to hijack someone's thread, but possibly the most important two pieces that I would want to make sure get included are the following: There is a post out there involving a guy who found a substitute pump for the BMW Pierburg. It is a Pierburg from an Audi and he found a working unit in a junk yard for $17! Then, another poster found that this Audi Pierburg can be had NEW on Amazon for about $100. It is a direct fit except for the connector and this may be the biggest help I have ever seen. The Audi pump puts out as much air as ours and is 1/3 the cost!

The second piece I believe is important is that there is no SIM to be built easily to fool the car and work around the whole stupid system that adds nothing except passing US emissions which BMW could not pass during initial cold starts only. After about a minute, the BMW emmissions were acceptable, but all this crap had to be added to "dilute" the emmissions for just 60 seconds at a cost of about $600 if you replace everything. So, what happens if you do replace everything with new BMW parts and you still have the error which will also set the SES light on the dash? The PowerChips people sell a chip designed to improve performance and whether you buy into the concept and value of the power chip for this purpose or not, they offer -as an option on your customized chip-the software that will replicate a European car that also has the SAP, but when it fails will not set the SES light or cause any issue whatsoever. You need to ask for this if you buy a PowerChip. It will just set a code that can be read, but will not cause you any issues. The Power Chip software widens the parameters the DME will accept as sufficient dilution of the exhaust to not set a SES. The DME looks for the correct signals from the O2 sensors telling the DME that the pump must be running as the O2s are swinging lean far enough. Well, what happens if your heads have excessive carbon build-up which we know plaques a lot of M5s as well as other E39s? This is what happened to me. I took my car to the Stealer as I had replaced everything including the valve and I knew the system was operating properly, but the SES light would not stay extinguished. The BMW techs confirmed that on my car, not enough fresh air from the pump was making it to the exhaust system due to carbon blockage in the heads. Cost to fix? $8000. It is a big job and there is an extensive post by a BMW mechanic of doing the gun drilling of the heads to clear the carbon. Next best solution is call the PowerChip folks and negotiate for just the Euro SAP software which took care of my SES light and allowed me to pass emmissions.

Bill

P.S. Blue, if you have not read the post from the M5 board on the BMW repair of a head to remove carbon build-up, you should search for it and read it. You might want to include it as well as it details the path the air must travel to get to the exhaust. #1 failure mode for SAP is condensation due to heat from the exhaust traveling by a faulty valve and hitting the cold pump. This can ONLY happen if the valve stays open due to crap being in there (soot, carbon, rust) keeping it open while the pump is not running allowing hot gases to hit cold pump. Second failure mode is relay contacts sticking closed as pump is over-driven to the point where it can only run for about 4 minutes at a time or it wil burn up. :thumbup:
 
#31 · (Edited)
a guy ... found a substitute pump for the BMW Pierburg ... there is no SIM to be built easily to fool the car and work around the whole stupid system
DISCLAIMER: I'm severely hampered doing SAS/SAP research because I, myself, have never dealt with the system and I really don't understand it at all.

I was culling while you posted this so take a look at the edits above.

Those links don't have the substitute Pierburg yet but they do have CN90's discussion that his pump was similar to that on the Audio, Mercedes Benz, Volvo, VW, etc.
- DIY: 1998 528i S.A.S Pierburg Air Pump Maintenance and Rebuild Info

As for the 'simulator' ... how does this thread look?
- Air Pump Simulator for 2 Bank all 6 Cylinders

there is an extensive post by a BMW mechanic of doing the gun drilling of the heads to clear the carbon. Next best solution is call the PowerChip folks and negotiate for just the Euro SAP software which took care of my SES light and allowed me to pass emissions ... read the post from the M5 board on the BMW repair of a head to remove carbon build-up
Gotta run right now ... but will 'try' to find those later ...

#1 failure mode for SAP is condensation due to heat from the exhaust traveling by a faulty valve and hitting the cold pump. This can ONLY happen if the valve stays open due to crap being in there (soot, carbon, rust) keeping it open while the pump is not running allowing hot gases to hit cold pump.

Second failure mode is relay contacts sticking closed as pump is over-driven to the point where it can only run for about 4 minutes at a time or it wil burn up.
Seems to me I should just link to your post above and title it "common failure modes". :)

EDIT: OK. So I did add your post so that others beneift. The 'coherent keyword-rich sentence' is more keyword rich than coherent, but, for better or worse, here is what it currently is (it will improve over time as my understanding of the SAS develops slowly).

- Where is the secondary air pump (1) & how to diagnose a secondary air system failure (1) & what are the most common two failure modes (1) & a DIY to perform SAS troubleshooting with the infamous fuse #107 (1) (2) & what to do when the SAP (1) clogs or freezes (1) or the diverter valve clogs (1), taking out the S.A.S. (1) (2) (3) (4) (5) (6) (7) & a S.A.P. replacement DIY (1) & a Pierburg air pump maintenance (1) & rebuild DIY (1) (2) & well thought out SAS/SAP simulation testing (1) & repair strategies (1).
 

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#32 ·
I need to learn to quantify my posts better! I should have said that no working SIMS have been made (to the best of my knowledge) for a 540. There have been some advertised for the I6s for a while, but not for the 540 AFAIK. I do not know whether the 540 is more complex or if the 540s DME looks for the appropriate current draw of the pump motor, but I believe it fair to say that a board made with the components shown here would not nearly satisfy the 540s DME. I would be very curious for the builder to talk me through what this uhm...circuit is actually doing. I can only assume that it uses the trigger that turns the pump on to flip the relays which somehow lower the voltage that the O2s report back when the SAP is supposed to be on. We know a properly functioning O2 sensor fluctuates fairly rapidly between about .1V and .9V with .5V being in theory an air-fuel ratio of about 14.7 to 1. When the car is lean, the voltage drops below .5V and when the car is rich, the voltage rises above .5V. The resistors need to be such that the O2 voltage still "swings", but is lower as if the pump is running and diluting the exhaust to be less rich. I have my doubts about this simple board working on a 540.
 
#33 ·
I finally got the car back from the customer, installed the good air pump from a wreaking yard out of another 525i (cost: $125, talked him down from $150), installed a new air valve on the exhaust and a new electric valve under the intake manifold (remove the cabin air intake assembly to make this job much easier: remove squeeze clip at front edge of air box, remove lid and filter, un-clip snorkel swing away and remove, lift out air box,) and checked the wiring. Here are my results:

The physical layout, or pin-out, of the Secondary Air Pump Relay and its connector with all the numbered positions that cn90 shows are the same as in his most excellent post. HOWEVER, the PRINTED WIRING DIAGRAM for the Secondary Air Pump Relay does not agree with how this car is wired, nor does it agree with how the Secondary Air Pump Relay functions and, most convincingly, does not agree with the wiring schematic that is MOLDED INTO THE SIDE of the Secondary Air Pump Relay. The 30 and 87 are reversed from the Printed Wiring Diagram with the pump connection being #30 and the fuse F107 (hot all the time) being terminal #87. There is no mistaking this. I did not get it wrong.

Look at the side of the Secondary Air Pump Relay and take note of the wiring diagram molded into the side of the relay confirming the layout of the switching portion of the relay and how it differs from the printed wiring diagram. #30 (going to the pump) is the switch while #87 (the f107 fuse) and #87a (the ground) are the two contacts that #30 switches between. This makes perfect electrical sense as well.

Most troubling is the part number that cn90 lists for the Salmon colored Secondary Air Pump Relay is the same number that is molded into the side of this car's relay: 12.631742 690. Also molded on the relay is: TYCO V23134-E53-X344. On the top, printed in black letters is: ++0109

This 525i has a build date of 3-01.

The pin-out for the Salmon colored Secondary Air Pump Relay (verify by actually looking at the diagram on the side of your relay):
30 - Pump
87 - Fuse f107, hot all the time, located under the carpet in front of the passenger seat.
87a - Ground located at right front side of the engine compartment.
86 - fuse f31 located in the drop down fuse panel in the glove box.
85 - DME Control Unit pulls this pin low which energizes the coil in the Secondary Air Pump Relay, switching pin 30 (pump) from 87a (ground) to 87 (f107, 12 volts) which powers the pump.

By the way, I am going to replace the Secondary Air Pump Relay in this car simply because the motor in the bad air pump I took out was completely melted. The obvious scenario that could cause this is a stuck relay that would allow the pump to run continuously to destruction. It is probably a good idea to replace it when you replace any pump because it is cheap ($10?) and operates under a significant load (13 amps).

~~~~~~~~~~~~~__/)_~~~~~~~~~~~~~~
 
#35 · (Edited)
...The physical layout, or pin-out, of the Secondary Air Pump Relay and its connector with all the numbered positions that cn90 shows are the same as in his most excellent post. HOWEVER, the PRINTED WIRING DIAGRAM for the Secondary Air Pump Relay does not agree with how this car is wired, nor does it agree with how the Secondary Air Pump Relay functions and, most convincingly, does not agree with the wiring schematic that is MOLDED INTO THE SIDE of the Secondary Air Pump Relay. The 30 and 87 are reversed from the Printed Wiring Diagram with the pump connection being #30 and the fuse F107 (hot all the time) being terminal #87. There is no mistaking this. I did not get it wrong...
Hi billj3cub,

Thanks for the follow-up on the 2001 525i wiring.

I just verified the Electrical Wiring of the 2001 525i and the "Published Data" is exactly as in the diagram I posted on the 1st thread.
In other words, the "Published Diagram" is the same for 1998-2003.
The flow is from battery ---> #30 ---> #87 ---> Air Pump.

In your case, your trouble-shooting procedure showed that:
The flow is from battery ---> #87 ---> #30 ---> Air Pump.

From an electrical standpoint, it does not matter because current still flows to the Air Pump.

I find it interesting that BMW changed their wiring in this manner, while it works fine, it makes no sense to switch the wiring pathways. Maybe they had too many bradwurst and German beers while working on the 2001 525i LOL!
 
#34 · (Edited)
It has been a while since I did my SAS re-build, but I believe you have it wrong just from looking at the relay stampings and from memory, at least on my 540i. I did not have the Bently then so I had nothing to compare to, but believe you are incorrect. 30 was power in from fuse 107 and 87 was N/O contact leading to pump. This is all from memory. You can see by looking under the relay at the relay holder...the large red wire is the constant power from fuse 107 and the other heavy gauge wire leading to the pump is on 87.
 
#36 ·
I bet that if he looks at the base of the relay socket, he will find a red wire on relay pin#30 and I think a heavy gauge brown wire on relay pin 87. You are of course correct CN90 that as long as you are checking during the first 90 seconds after a cold start everything is common. After that, he should find that only pin #30 stays hot coming from fuse 107 and pin 87 will drop to nothing unless the relay is bad and is staying in the N/O position full time..
 
#37 ·
I also want to add the following comment for people reading this thread on how to check relay operation, there is a BIG difference between checking relay when it is attached to the car and when it is removed entirely from the car.

- With relay in the car, lift it gently up a bit so all the legs are exposed (about 2mm or so), so the voltmeter probes can reach the relay's legs for testing.

- With relay out of the car, one can only check for continuity or open circuit, unless one applies voltage to the appropriate pins.
 
#38 ·
I believe it is safe to assume that 540iman and cn90 are correct in their descriptions of the wiring scheme in their cars while at the same time I have no doubt that the pin-out and function I described on the 3-01 525i that I just worked on is correct as well. So, I can only surmise that the discrepancy between these cars must lie in different Salmon colored Secondary Air Pump Relays. If my relay was installed in your car then the 30 terminal (you say is fuse f107) would switch between 87 (to your pump) and 87a (ground) which would blow the f107 fuse.
cn90 listed the Secondary Air Pump Relay part number in his original post from a parts list, presumably not from actual inspection of his relay. Could you, 540iman and cn90 and anybody else reading this, please inspect your relay and report back on four observations?:
1) What are the numbers molded into, and/or printed on your Salmon colored Secondary Air Pump Relay?
2) What is the switching scheme in the diagram molded into the side of your Relay? Mine shows 30 as the switch with 87 and 87a as the two terminals that 30 switches between. It is this diagram on my Relay that is in direct contradiction to the Printed Wiring Diagram that cn90 posted where 87 (it shows pump) switches between 30 (it shows fuse f107) and 87a (ground). This is the main item that I would like to have verified.
3) Does 30, 87, 87a, 85, and 86 molded into the underside of the relay right next to each terminal match up to the pin layout in the connector as shown in cn90's original post? Particularly, verify if there is a 87a and not just two 87's (or something else) next to each other.
4) Does 87a in the connector show continuity to ground?
The upshot of all this is that posters like MaximeM and I would get confused (I certainly did) following cn90's post. Also, most importantly, if you replaced your relay with part number: 12.631742 690 (which is the number on my relay) as listed in cn90's original post, and put it in your car it would blow the f107 fuse the moment you plugged it in (unless the 87a terminal in the connector does not go to ground like the printed diagram says). That would be bad. That is why I am taking the time to resolve this so there is not a Forum Post Bomb waiting to blow up the f107 fuse on some non-electrical noob. :cry:
By the way, I did verify the function of my relay by driving the 85 and 86 pins with a 5 volt signal and found that pin 30 switched from 87a to 87. Our '02 M3 has the same SAS system so when we get it back from the painters I will verify the M3 wiring, relay and function as well. :thumbup:
 
#43 · (Edited)
..If my relay was installed in your car then the 30 terminal (you say is fuse f107) would switch between 87 (to your pump) and 87a (ground) which would blow the f107 fuse.
This is interesting because in this particular setup, the SAS Relay schematic is designed in such a way that 87 and 87a are always in continuity, i.e., actually the same circuit. So your customer car relay is different than the earlier models from 1997-1998?

a. SAS Pump OFF:
#30 just opens, not connected to anything.

b. SAS Pump ON (when 85-86 is activated, it pulls a magnet and the relay's arm, which pivots on #1, swings from #2 ---> #3 in the pic below):
#30 ---> 87a ---> 87 ---> SAS Pump.



PS: For a primer course on Bosch relay, i.e., how it works and different configurations etc., people may want to look into this schema for headlight by Bosch relay (switching between 87 and 87a for low-beam and high-beam, which is very different from the SAS Pump):

http://www.bcae1.com/relays.htm

---
 

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