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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 02-12-2012, 06:47 PM
mrwalters mrwalters is offline
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2000 323CI reoccuring EML light after fix

My 2000 323CI had the EML light come on a month ago. After getting the codes read by our mechanic he determined that it was the MDK. Unfortunately for my year model it was an expensive fix because the tps sensor was a part of the entire throttle body and had to be replaced as a whole unit.
Got the car back and it drove fine for 3 weeks, then the problem came back but this time different.
The first time the car would limit itself to about 40mph and it wasnt an intermittent problem. Now when it happens the car limits itself to about 5 mph. It mostly happens when I am letting off the throttle and the car begins to decelerate.
twice the gearbox light with ! in it came on and after turning the car off and then back on it drove fine.
I am mechanically inclined and would appreciate your input on what may be the culprit. I am considering that it may be a loose connection. Also, I have the old MDK and I would like to test it to see if it is faulty. Does anyone know the pinout so I can plug in a meter to it. I have multimeters and o scopes so the electrical testing shouldn't be a problem if I had a guide to go by. I could not find one anywhere on the internet.
I just purchased a carsoft pc app and the round connector that plugs underneath the hood.
My engine is the m52.
any help is GREATLY appreciated and when I find out what it is I will post in DETAIL what was done to fix it.
Thanks so much
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  #2  
Old 02-19-2012, 03:57 PM
mrwalters mrwalters is offline
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Got the car back from the mechanic. He had to replace the mdk again after finding no other faults. A day after I get it back the eml light comes on for a second while driving. I'm assuming it's not fixed.
Any ideas.
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  #3  
Old 02-19-2012, 04:22 PM
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smolck smolck is offline
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What is an MDK?
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now, go burn your Man Card, and buy yourself a Camry....
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  #4  
Old 02-19-2012, 04:54 PM
mrwalters mrwalters is offline
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Throttle body and tps sensor
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  #5  
Old 02-19-2012, 05:40 PM
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smolck smolck is offline
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Quote:
Originally Posted by mrwalters View Post
Throttle body and tps sensor
How do you get MDK as an acronym for that?

I'd ask where he is getting his throttle bodies from and if he is using blue or yellow label. The yellow label is interchangeable and I found to be much more reliable on my 323. And it ate 2 blue ones before I switched to yellow.
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now, go burn your Man Card, and buy yourself a Camry....
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  #6  
Old 02-19-2012, 05:49 PM
mrwalters mrwalters is offline
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I didn't make up the nomenclature.
They were new from BMW.
I don't know Their was a difference in the label colors.
Now that it's been changed out twice and the fault is still occurring where do I go from here. I love the car but this problem is making it too unreliable.
It only occurs when I let off the throttle and coast.
Thanks.
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  #7  
Old 02-19-2012, 06:28 PM
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smolck smolck is offline
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Quote:
Originally Posted by mrwalters View Post
I didn't make up the nomenclature.
They were new from BMW.
I don't know Their was a difference in the label colors.
Now that it's been changed out twice and the fault is still occurring where do I go from here. I love the car but this problem is making it too unreliable.
It only occurs when I let off the throttle and coast.
Thanks.
You need to find out where they are getting these throttle bodies and what color label they used. Get a yellow label one from a reputable place and it should fix your problem. That is the only thing I can tell you.
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now, go burn your Man Card, and buy yourself a Camry....
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  #8  
Old 02-19-2012, 07:07 PM
mrwalters mrwalters is offline
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If it does it again I will look at the color of the throttle body myself, but because they are new from bmw I dont see how it would make a difference and cause it to go out in a few days. I'm beginning to think that it is something else. I have the old blue label throttle body sitting in my garage. From what I hear the internal tps is a rheostat.
Does anyone know of the pinout to the throttle body so I can test the rheostat for opens. that way I can know if the original one even had any problems. If it didnt then the problem resides elsewhere.
I have a pacman connector and just got carsoft off ebay. If I knew how to diagnose it and avoid the mechanic I would.
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  #9  
Old 02-19-2012, 07:18 PM
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smolck smolck is offline
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Quote:
Originally Posted by mrwalters View Post
If it does it again I will look at the color of the throttle body myself, but because they are new from bmw I dont see how it would make a difference and cause it to go out in a few days. I'm beginning to think that it is something else. I have the old blue label throttle body sitting in my garage. From what I hear the internal tps is a rheostat.
Does anyone know of the pinout to the throttle body so I can test the rheostat for opens. that way I can know if the original one even had any problems. If it didnt then the problem resides elsewhere.
I have a pacman connector and just got carsoft off ebay. If I knew how to diagnose it and avoid the mechanic I would.
Ah, I missed where you said it was new. If that is the case then it might be your wiring harness. Also, if your MAF completely crapped out you would get the trans limp mode and similar issues. May want to check that too.
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Quote:
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now, go burn your Man Card, and buy yourself a Camry....
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  #10  
Old 02-21-2012, 05:36 PM
mrwalters mrwalters is offline
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OK I may have figured out.
Earlier today I fixed the intermittent and sometimes non functioning convertible top due to a broken wire and semi-broken wires in the roof itself. works like a champ now and when i clear the codes none reappear!
Makes me think that a similar problem may be happening in the engine.
Here are the codes I pulled up with carsoft:
243- misfire cyl #6 (could be caused by limp mode)
246- o2 sensor (also could be caused by limp mode)
119- throttle sensor value off from mass air flow sensor (happens when tps inside mdk is not functioning)
172- pedal position sensor short (culprit and is located in throttle body)
173- motor throttle valve short (culprit and is located in throttle body)
169- limp mode

So someone please chime in here. I had the throttle body (MDK) replaced professionally twice with new units and the problem comes back. From these codes it looks like a short in the wire loom or connectors. Im sure that the second time around they checked the connectors so I am leaning towards a shorted/broken wire in the loom. Does anybody know where the the most common place for breakage is? I found the broken wires in my top in the EXACT same place others have found them in these forums. Your help is much appreciated!!!!!!!
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  #11  
Old 03-12-2012, 09:13 PM
mrwalters mrwalters is offline
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So its been a few weeks now and I can pinpoint when the problem occurs.
The EML, Traction, and gearbox light come on only first thing in the morning. This happens after I put the key in the ignition and even before the engine starts. I drive it a block at (fastest it will go is 3mph) and I turn the car off for 30 + seconds and restart it and all is well.
What could cause this.
Also, when coasting to a stop the Eml light occasionally comes on. All other times the car drives fine.
Any ideas?
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  #12  
Old 04-10-2012, 06:30 PM
mrwalters mrwalters is offline
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I have seen many people post problems and never state the solution.
I finally got the solution.

After taking it to another BMW specialist he couldn't figure out the problem and suggested a 3rd throttle body... stating that the solid state electronics in the TB were bad, which simply don't exist everything is passive in the TB. So he wasn't much of an expert but he charged me $260 for his wrong diagnosis.

I ordered a used Engine wiring harness off of eBay. It included the 52 pin connector that plugs into the DME and drives most of the engine electrical. I opened the rubber loom with scissors and traced the 10 wires that went from the 52 pin connector to the MDK (throttle body).
I used an O scope and an AA battery to check for loose connections in the wires on the new* harness. After determining that the 10 wires and connector were good I meticulously took the old connectors out of the 52 pin mull-ex connection (two 26 pin connectors) making sure to note the wire colors and where the pins went to. 8 wires went to the gray connecor in the 52 pin socket, and two went to the black connector. The wires in the Gray connector were going to sensors, of which there are 4 potentiometers in there. Two pedal sensors and two throttle sensors. When a signal is lost from either one pedal or throttle sensor it causes EML limp mode that limits the car to around 40mph. When all signal is lost from either the pedal or the throttle pots it puts the car into 5mph limp because it has no clue where the pedal is pushed and/or how far the throttle is open. If the car is driving fine and it suddenly goes into 5mph limp mode and the codes indicate a throttle or pedal position sensor then chances are that it is a loose shared common connection to from the DME to the MDK potentiometers since both the pedal and the throttle pots share one common wire between them and use a separate sense wire for each pot.

So to reiterate.
4 pots, four sense wires, and two common wires.
If I had bought a new harness I would have rewired the entire engine but because it was used I wanted to eliminate all other possibilities and only use the connections for the MDK/DME plug.
After wiring it up for an hour I turned the car on and checked the codes with PA soft 1.3.6
Originally had 7 codes on the DME. Down to 1 after clearing and after driving the past week all codes are now gone. The culprit was the round connector on the old wire harness, which is still hanging in its old place. I simply bypassed the old plug and ran the wires separately outside the old loom.

I have heard that this connector is a know problem and if after replacing the TB and the problem still occurs chances are its the harness. A new harness isn't much. I found one for $380 new and had I been 100% certain this would fix it I would have just bought that rather than take apart a used harness.
All in all this loose round plug cost me over a $1500 in mechanics and a lot of heartache and in the end I was the one who had to solve it.

I hope this is a help for people who have the same problem.

here is a pin-out of the connection from the throttle body to the DME, remember this is for a 199 or 2000 E46 with a 52 series engine, the 54 engine has TPS sensors that cane be removed separately from the TB.

Number on the left is the pin to the round MDK throttle body (you can see the number in the end of the connector if you look closely)
Number on the right is the pin in the 52 pin DME connector. 1-26 are in the gray portion of the connector, 27-52 are in the black connector. These are labeled on the connectors themselves when you pull them out of the 52 pin locking connector.

1 RED/GREEN STRIPE PIN 4 GRAY CONNECTOR ?
2 RED/YELLOW DASH PIN 7 GRAY CONNECTOR ?
3 BLACK/YELLOW STRIPE PIN 9 GRAY CONNECTOR PEDAL POT #1
4 BROWN/WHITE STRIPE PIN 20 GRAY CONNECTOR COMMON TO POTS (CANT REMEMBER IF IT IS THROTTLE OR PEDAL)
5 BLACK/GREEN STRIPE PIN 10 GRAY CONNECTOR THROTTLE POT #2
6 BLACK/PURPLE STRIPE PIN 12 GRAY CONNECTOR PEDAL POT #2
7 BROWN (#813 ON IT) PIN 14 GRAY CONNECTOR COMMON TO POTS (CANT REMEMBER IF IT IS THROTTLE OR PEDAL)
8 BLACK (#814 ON IT) PIN 19 GRAY CONNECTOR THROTTLE POT #1

9 GRAY/YELLOW STRIPE PIN 43 BLACK CONNECTOR THROTTLE SOLENOID MOTOR
10 GRAY/GREEN STRIPE PIN 44 BLACK CONNECTOR THROTTLE SOLENOID MOTOR

To make sure the DME is working check pin 1 (red/green wire) and pin 2 (red/green/yellow wire) on the 52 pin connecotr, they both need 5VDC to ground. IF 5V is present then chances are the DME power supply is OK and the problem lies elsewhere.
I got code 172 and 173 which indicated the wires were shorting to each other. Upon investigation I didn't see any shorting so maybe it also means that it could be a slight connection and the DME doesn't know the difference.
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  #13  
Old 04-10-2012, 09:51 PM
geoffba geoffba is offline
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Great write up and congrats on finding the answer. I have only had my 03 325i for 4 weeks and it seems I have some electrical gremlins similar to this. Not exactly the same problem, but this is great information and it may be where I get to some time down the road. Thanks for posting and I will make sure I post a response if I figure out what is going on with my vehicle.
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  #14  
Old 04-11-2012, 07:12 AM
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catso catso is offline
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Congratulations on finding the solution. Intermittent electrical problems are the most difficult to diagnose and it requires someone who won't give up.
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  #15  
Old 04-11-2012, 07:15 AM
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Kudos on the dective work and write up.
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  #16  
Old 04-12-2012, 06:35 PM
mrwalters mrwalters is offline
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Also, after thinking about it code 172 and 173 indicate a short between potentiometers. The DME sends a pulse to each of the pots at a separate time to test the connection, if they voltage is sensed on another wire then it believes there is a short in the wiring which makes perfect sense.

Since both sets of the two pots share a common wire between them the voltage applied to the pot is sinked to the common wire and travels back to the DME on the brown wire. When the common wire comes loose the electricity flows through one pot, doesn't stop at the common wire because it is open and travels to the second pot and back to the DME on the second pots wiring.
A loose common (ground) connection between the DME and the throttle body will throw a code of 172 or 173.
Examining the wiring harness I would believe it would be hard to have an actual short between wires without some sort of catastrophic problem such as a a horrible chaffing or fire that causes the insulation to wear away.
Code 172/173 means your brown wires (pin 14 or 20 on DME 52 pin connector or pin 4 or 7 on MDK throttle body) have come loose.
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  #17  
Old 04-07-2013, 08:05 AM
g_collins90 g_collins90 is offline
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Has anyone in England tried the solution of the eml light
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  #18  
Old 04-24-2013, 12:23 PM
tommytoyz tommytoyz is offline
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I changed out my MDK and engine wire harnes, and so far so good. My EML and ASC lights would come on and the car would go into limp mode. Since I wasn't sure if the problem was with the MDK, as the failure codes suggested or with the wires/connectors, I changed them both to be sure.
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  #19  
Old 06-27-2013, 08:28 PM
nemotw nemotw is offline
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Thank you for the solution!! I've already replaced my Throttle Body on my 2000 BMW 328i with a used one. Unfortunately, it broke down and tripped the codes again.

FYI, I obtained a throttle valve diagram from the BMW WDS and I noticed that the following Pinout to the DME was different.
6 BLACK/PURPLE STRIPE PIN 12 GRAY CONNECTOR PEDAL POT #2

WDS states that Pin 6 on the MDK connects to Pin 16 on the DME:
6 BLACK/PURPLE STRIPE PIN 16 GRAY CONNECTOR PEDAL POT #2

I haven't tested it yet so I'm not sure if the WDS is correct or if it's a misprint.
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  #20  
Old 07-01-2013, 01:47 PM
nemotw nemotw is offline
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I just finished (inline wire) splicing in a round MDK throttle connector from a junk yard (528i) into my engine wiring harness. This cleared the short-circuit codes that my DME was throwing.

The BMW WDS was correct. On my 2000 BMW 328i, the wiring was:
6 BLACK/PURPLE STRIPE PIN 16 GRAY CONNECTOR PEDAL POT #2

I think an alternative way to fix this problem is to replace the pins in the connector.
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