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And Donna, what Qsilver said: test #9. Very easy to do, and gives you tons of info.
FYI, when running, my alt shows about 13,7V and my car is a 2003, so quite close to yours in terms of manufacturing. Not sure about the alternator brand.
Might need to swap those brushes out as mentioned above. but do test #9 first.
If you swap the brushes, test the bearings too.

Cheers
 

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Another moronic tower...Do not tow a bimmer through suspension parts...
There is one hole on the front, one on the rear.
Once the car is lifted, secure through the wheels, not the suspension.
Make sure once you have the car back everything is fine with the suspension.
It was not towed by the suspension, it was only secured to the flat bed via the suspension bits. Still not ideal. At the minimum, I would have used nylon straps rather than metal hooks to the arms.
 

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Based on the symptoms, I'm going to have to disagree with you on this one. The failsafe mode is simply a sign of the low system voltage in this case. The transmission computer uses quite a bit of juice to do it's thinking, and when you cut the power down significantly, you pay for it in limited function.

Happened to me on the '01 530iA, and the first thing to go was the shifting. I though I had a blown transmission- turned out later that I needed a new alternator... Another reason I love my 5 speed, now!
+1, same happened to me when my alternator failed.
 

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(I am just now starting to flip through the Bentleys to see how to test the alternator while the battery is charging).

While it's charging, may I ask if it matters whether I charge the battery from the engine compartment or from the trunk?

BTW, it's taking 4 amps, even an hour after I hooked it up!

Safest to charge from the engine compartment, less chance of igniting battery gases. That is why BMW recommends that way.
 

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Discussion Starter · #27 · (Edited)
If you run TEST 9 ... With the engine running, you should have voltage numbers between 12.8 - 14+ volts
Hi QSilver7,

Thanks for the advice (we'll need to add this to the eventual alternator-testing DIY).

I have the high instrument cluster (i.e., two buttons, 20-digit readout at the bottom center, oil-service interval to the left) and the high MID (BC button); and I already unlocked it (for the KTMP tests prior) but, for some reason, it showed up as LOCK=ON for the tests .

I promptly re-un-locked it, using these three OBC references:
- OBC Tests (Unlocking the High & Low Instrument Cluster)
- Summary of how to tell if you have the high or low instrument cluster
- Exploring the E39 OBC
which basically consisted of adding the last five VIN digits and pressing the RESET button that many times in test #19).

With or without the car running, the voltage remained below 12 volts.

But, reading page 121-12 of the Bentleys tells me that it can take up to 15 seconds before a BMW alternator puts out correctly ... so I should have rev'd the engine and waited fifteen seconds while doing so (note to self and others).

 

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Discussion Starter · #28 · (Edited)
when running, my alt shows about 13.7V ... Not sure about the alternator brand
Mine showed less than 12 volts at idle. I forgot to rev it up so I'll try that next and see if it changes the number at all ... but it's looking like the alternator is kaput (maybe that's the noise I heard over in this thread).

As for the brand of alternator, I was confused by REALOEM because it showed three for my serial number:
- 90 amp Valeo alternator
- 120 amp Bosch generator <=== why do they call this a "generator" and not an "alternator"?
- 120/140 amp Valeo alternator

So I took a mechanic's mirror and snapped a shot to get your advice. (This shot below is flipped horizontally so that we can read the mirrored lettering.)

I can make out "BOSCH120", and the number "0 124 515 050" and "NCB1 14V 70-120A" and "7 501 595 GL" and "Made in Great Britain 806".

I hope it's the same one cn90 rebuilt ... 'cuz then the parts would be the same ... but I doubt it (given the different year).

Is the right approach either to rebuild (as per cn90) or to replace with a 1:1 Bosch 120 amp remanufactured unit? Or new?

 

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Discussion Starter · #29 · (Edited)
I usually pull my battery out completely to charge it.
It seemed suspicious to me that the battery, even after hours of charging from the engine compartment, was still sucking 5 amps ... so I moved it to the rear, after disconnecting the negative cable to isolate just the battery.

Guess what. A full 5 amps. So it didn't make any difference. I'll leave it charging overnight. (Just checked after about 4 hours, it's still charging at 4 amps.) I need to go on an interview tomorrow (I pushed it off today ... got laid off ... no fun) ... anyway ... it will be interesting to see how far the E39 can go on a full battery charge ...

Doing some research, REALOEM lists the 120 amp alternator as part number 12317501599 for $561. However, a remanufactured Bosch 120 amp alternator is easy to find at roughly $175 (plus tax & shipping); but I may take up cn90's advice and go for the rebuild when I figure out what is really wrong with diagnostic tests (it could be the belts, for instance). Time to parts will be a major consideration ... as is the troubleshooting and R&R procedure.

For troubleshooting:
- Pelican has a 3-series alternator troubleshooting DIY
- The BMW 2002 FAQ has a description of the charging system
- Test of a 120 amp BMW alternator puts out 142 amps (youtube)

 

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Discussion Starter · #30 · (Edited)
For the record (from the Bentleys, starting at page 121-5), it looks like the first test is to check the specific gravity of a fully charged battery.

0. Check that the cables are tight and free of corrosion
1. Load the battery with 15 amperes for one minute (by turning the headlights on with car off)
2. Remove the sticker on top of the battery covering the cell caps
3. Remove the cell caps
4. Test the specific gravity with a hygrometer

The next test seems to be the battery open circuit voltage test.
1. Load the battery with 15 amperes for one minute (by turning the headlights on with car off)
2. Put a DMM across the battery terminals to check voltage
3. See chart below for analysis

This is the load voltage test:
0. Disconnect the battery cables
1. Apply a 200 amp load for fifteen seconds
2. Check the voltage across the battery terminals
3. See chart below for analysis
 

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Discussion Starter · #31 · (Edited)
I usually pull my battery out completely to charge it.
That seems to be what the Bentleys recommend, on page 121-9.
- Remove battery from trunk to charge
- Keep charge current below 6 amperes
- Keep charge voltage below 16.5 volts
 

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Discussion Starter · #32 · (Edited)
I had the same symptoms when my alternator went south.
It looks like I have an alternator with multi-function control (MFR). For MFR alternators, the red battery light goes on given any of the following:
- Drive belt failure
- Electrical fault
- Excitation circuit fault
- Defective controller output stage
- Fault in charge line
- And finally, alternator fault

Yikes. These seem more complex than just whether the alternator is putting out or not ... :(
 

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Discussion Starter · #33 · (Edited)
Moving on to summarize Bentley suggested checks for the charging system, it seems the first test we've already done which is the battery voltage test under charge:

0. Check voltage across battery with key off
1. Check voltage across battery with engine idling
2. Wait at least 15 seconds for the alternator output to rise
3. Results should jive with the chart below
Note: Also check voltage from the engine + terminal to ground (it should be the same).

While I read elsewhere a test of the alternator is to disconnect the battery negative cable while the car is running, the Bentleys expressly forbid that. Curiously, they suggest not using analog multimeters in favor of digital multimeters.

The next step is to check for battery voltage at the alternator:
- Completely remove engine air filter housing as described below

Once access to the alternator is gained (V6 is vastly easier than V8):
- Check the voltage from the alternator #30 post and ground
- It should be the same as the battery voltage

Now disconnect the harness connector to the alternator:
- Check voltage from terminal 15 and ground (field voltage)
- It should be the same as the battery voltage

Last is the operational check as shown above. If this fails, the alternator is toast.
 

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Discussion Starter · #34 ·
If you confirm it is indeed your alternator, here are some DIYs for alternator replacement. Sorry, don't have one for the 525.
\

Thanks Fudman for gathering up the BMW alternator R&R DIYs together as little nuances always get me when mine is different than the description so it helps to have multiple descriptions.

Here's what the Bentleys say (page 121-15) for the I6 engine that I have:
0. Remove air filter housing
1. Remove alternator drive belt
2. Remove radiator cooling fan and fan shroud
3. Unbolt power steering fluid reservoir & bracket (keep hoses attached)
4. Disconnect alternator air-cooling tube
5. Disconnect wiring from rear of alternator
6. Remove upper mounting bolts from alternator
7. Remove lower mounting bolts from alternator
8. Remove idler pulley cover and retaining bolt if necessary

Of course, the devil is in the details! :(
 

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Discussion Starter · #36 ·
Translation error?
Yeah, or maybe, in German, there isn't a reverse distinction between the alternator (rectified AC) and a generator (DC).

This morning, the battery charge dropped to less than an amp (as it's supposed to), so that battery must've been deeeeep discharged. The fisheye is still hard to tell, but, it looks pretty green when I use a flashlight.

I'm a bit scared, this is one job that disables the car totally while in progress (and I tend to take my time when I'm not sure what to do). The instructions for replacing the alternator (I may as well replace the belts too) don't look too bad. I'll need to read all the DIYs first (I spend more time researching & reporting than doing sometimes).

Are these my only viable options if it's the alternator?
- Replace the alternator with a Valeo or Bosch 120 amp unit, new or refurbished
- Rebuild the alternator with quality components (ala cn90)

 

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Just an FYI: when ever the car loses power...the instrument cluster/OBC "RE-LOCKS" itself...so that's why you had to UNLOCK it again.

Good luck with the alternator replacement. :thumbup:
 

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bluebee,

By definition, a generator is a generator. It basically produces current, which could be either DC (bicycle) or AC (household current or car current).
So the German is correct.

Rebuilding the Alternator takes time to order parts.
Maybe easier to order a rebuilt Bosch from local autoparts store.

Too bad you don't live in L.A. otherwise my cousin could help you (he owns a BMW indy shop).
Perhaps another member from San Jose can give you a hand.
 

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Discussion Starter · #39 · (Edited)
The instructions for replacing the alternator (I may as well replace the belts too) don't look too bad.
I spoke too soon. The Bentleys stink when it comes to the alternator removal.
And there's no 1:1 DIY for the 525i (AFAIK).

Here's what (little) the Bentley says about the four steps:
1. Remove air filter housing (Bentley 121-15, not too bad)
2. Remove alternator drive belt (Bentley 020-16, almost wholly useless)
3. Remove radiator fan and shroud (Bentley 170-14, nearly useless)
4. Remove alternator (Bentley 121-15, pretty sparse, but probably usable)

1. Alternator removing & installing (6 cylinder engine) page 121-15
Note: The alternator removal instructions aren't too bad; they don't show many pics; but they describe the tasks ...
- Disconnect negative battery cable
- Remove complete air filter housing
* Loosen intake duct hose clamp at throttle assembly
* Loosen clamp and remove idle control hose from intake duct
* Disconnect idle speed control valve harness connector
* Disconnect harness connector from mass air flow sensor
* Remove air filter housing mounting screw
* Disconnect vent tube
* Loosen air intake duct clamp
* Lift air filter housing out of engine bay

2. Remove alternator drive belt (see page 020-16)
NOTE: These Bentley alternator belt removal instructions are almost useless!
* The inner, longer drive belt turns the alternator, waterpump, and power steering pump
* The outer, shorter drive belt turns the AC compressor
* 32mm cooling fan nut has left hand threads
* If necessary, remove fan cowl from radiator
* Use long-handled wrench to turn A/C belt tensioner release lug clockwise against spring tension
* Remove AC belt
* Similarly turn main engine drive belt tensioner lub clockwise and remove belt (presumably the longer belt)
* Some models have a dust cover over belt tensioner release lug, which must be pried off prior to removing belt

3. Remove radiator cooling fan and fan shroud (see page 170-14)
Note: These Bentley instructions are horrible for removal of the fan and shroud!
* It is possible to remove the fan without the shroud
* From the top of fan shroud, remove expansion tank bleed screw
* Remove expansion tank locking tabs
* Push top of expansion tank oward engine and lift to free from lower mounts
* Remove two expansion rivets in upper corners of fan shroud
* Unclip expansion tank bleed hose located under shroud
* Remove rubber trim strip between top of shroud and radiator
* Using 32mm wrench on fan clutch nut, turn wrench clockwise (working from front of car) with BMW special tool 11 5 040
* At the same time, counterhold pulley (which pulley?) with BMW special tool 11 5 030
* The radiator cooling fan 32 mm nut has left-hand threads
* For M54 engines, unclip AUC air quality sensor from shroud
* Disconnect auxiliary coolant pump from base of fan shroud (what is this?)
* Lift fan and shroud together out of engine compartment
* To replace fan clutch, remove fan mounting bolts and separate viscous clutch from fan

4. Remove alternator (Bentley page 121-15)
- Unbolt power steering fluid reservoir and bracket & suspend
- Disconnect alternator air-cooling hose
- Disconnect wiring from rear of alternator
- Remove upper alternator mounting bolt
- Remove lower alternator mounting bolt
- If idler pulley interferes, remove pulley cover & retaining bolt

As you can see, the Bentleys are really lousy. They don't provide pictures, they skip what looks like a half dozen steps at a time, and unfortunately, there doesn't seem to be a 535i -specific DIY extant. For example, the Bentley says "disconnect auxiliary coolant pump" but it doesn't even provide a picture. I didn't even know we had an auxiliary coolant pump at the base of the fan shroud, for example. I would think a picture would be appropriate. Likewise, the instructions for the belt removal are almost wholly useless. Frustrating this is.

Anyway, this is a start. I think the Bentleys are terrible for this though. I'm going to look at some of the DIYs now to get clues.

 

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In brief, the Bentleys are just being redundant to a T.

You need to get all the air-filter related bits out of the way... You need to remove the fan/shroud (and all that that entails) simply to be able to remove the belt and unbolt the alternator-related bits.

The auxiliary pump. If you have one, it should be clamped to the lower left (driver-side) corner of the fan shroud along with attached hoses; these all have to be slipped out of the shroud so that you can pull the shroud up and out of there (with the unbolted clutch fan). It's small but easy to see from underneath if you have the bottom cover off.... Do it once and you'll be the master.
 
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