1987 325 M20b27 electrical issuse? - BMW Forum - BimmerWerkz.com
3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

 
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#1 (permalink) Old 06-25-2009, 10:26 AM
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1987 325 M20b27 electrical issuse?

Hello, Im new here and recently my 325 starting having intermittent problems with the engine randomly shutting off, at first i thought it was a problem with my fuel system and ive checked all that out with my Bently and Chilton books, my fuel system seems fine, i even replaced my fuel filter and my ignighter coil and it still had the problem.

Now come two weeks later and i havent really been driving it unless it was jus to the store and it would still randomly stall, but now it has gotten worse and it is no longer intermittent and just doesnt work.

Anyways getting to the point....I have no spark and i tested my Motronics with the table on the Bentlys Section 6 page 46, and the only thing that failed was the power supply to control unit on both pins 18 and 35, i got 0v, i checked my main and computer relays they seem fine, i tried swapping them with the other relays, i visually inspected my fuse box for bad fuses, those all seem to check out.

So i had a major intermittent problem that caused my engine to randomly shut off and it is no longer intermitten, I have fuel, no spark, no to voltage to my DME, relays and fuses SEEM fine, i havent tried buying new ones. I ohm tested my position and reference sensor by physically removing them and also testing the DME harness.

Im currently stuck, where do those two pins (18 and 35) get voltage from, and where does that get its voltage from? My DME isnt fried is it?


Ive checked for my reference pin.
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#2 (permalink) Old 06-25-2009, 10:58 AM
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No spark would point me in the direction of the crankshaft sensor if not that you have a bad ground.but with the intermittent failure it points to a sensor.

I would say at this point that the ECU is NOT bad.

Do you have all dash lights when you turn the key to pos II ? if you do then the ECU should be fine

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#3 (permalink) Old 06-25-2009, 11:06 AM
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About the grounds, i was using the chart from the bently manual as stated above, and it had tests for grounds and those all passed, and i was wondering if those tests are for all the grounds in the car, and i tested both reference and position sensors and the ohms were within tolerance, is there another way to test them?
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#4 (permalink) Old 06-25-2009, 11:09 AM
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Post Electrical Troubleshooting Manual (ETM) link

http://www.wedophones.com/Manuals/BM...g%20Manual.pdf

Those pins get power from the main relay. The main relay's power source is hot at all times.
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#5 (permalink) Old 06-25-2009, 11:52 AM
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So then i guess it seems to be narrowed down to the sensor and my main relay, hopefully i can try both of these this weekend and ill post my results Thank you very much for the wiring diagram too.

Sry for posting the same thing on more than one forum, but i had posted previously on just one forum and had recieved no responses :P
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#6 (permalink) Old 06-25-2009, 11:59 AM
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Oh also another detail that i cant believe i forgot to mention, shortly after my problem was no longer intermittent (i.e. not starting at all anymore) my battery wouldnt stay charged, it had just sat for a couple days before i went to go work on it again and the batter was dead, nothing was left on no lights, interior or ext, the keys werent in i had my stereo removed just to avoid this happening, but it did happen so i put a battery charger on there for a day and 2 days later it was dead again

I had just bought a new battery in February so i could goto the drive-ins cause it wouldnt start after jus a few mins with the radio

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#7 (permalink) Old 06-25-2009, 02:11 PM
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Worth a lurk (pun intended)

Constant dead battery?? - Bimmerforums - The Ultimate BMW Forum

I'm on five or six of these discussion boards, and tap freely from all of them.

Hope this helps.
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#8 (permalink) Old 06-26-2009, 12:29 AM
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I bought some fuse relays today, gave me voltage to my dme, but still no start. I'm going to pick'n'pull tomorrow afternoon to get some new sensors and whatever else i find of use while im there
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#9 (permalink) Old 06-29-2009, 01:37 PM
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I'm still trying to get my hands on some sensors, so if it isnt the sensors, im not too sure what to do after that if the sensors dont work...i might have to scrap it
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#10 (permalink) Old 06-29-2009, 01:45 PM
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Another troubleshooting guide

http://www.bavauto.com/newsletter/20...newsletter.pdf

You want to make sure you don't overlook something that turns out to be an inexpensive fix.

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#11 (permalink) Old 06-29-2009, 02:55 PM
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Hey thanks, this pdf is very informative, ill see what i can do with it later this week. Thank You.
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#12 (permalink) Old 03-06-2014, 01:25 AM
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Another Electrical issue/problem that's similar

Hi.
I went page by page up to page 14, in the Series specific forum, yet no luck.
If this has been addressed before, just point me to it, and I'll read it.

Here goes: I put the new battery in backwards, in a 1987 325i.
yes, i did. Now, first there was smoke coming from wires toward the rear (coming out from under the driver's side rear door area) , then a few seconds later (while I was undoing this wrong I'd done) thesmoke started coming from under the front hood on the driver's side. I went and got another new battery, put it on, started the car, drove it from the parts store to the house, and when I turned the key OFF the red battery icon light came on and stayed on. So I took the negative cable off, put the black rubber cover on the post and started looking for information on the internet.
The car was driven 5 blocks away and back for laundry a few days ago. The negative wire was disconnnected while there and again back at the house. Same thing again with the battery light.

I am broke and it's not my car, but I'm responsible for the current problem, so I'm looking for the least expensive way to fix it. I'm starting to think I gotta huge expense coming up tho.

If someone did the same mistake as me, with the same results, how did you fix it?
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