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Electrical Gremlins

5K views 9 replies 3 participants last post by  bluebee 
#1 ·
1998 528i - Originally suspected the ignition switch but I really dont think my issues are related. Symptoms: key fob not operating
right head light remains on all the time. (disconnet battery to prevent drain daily)
Stereo works 90% of the time but sometimes will not turn on at all.
only the passenger side view mirror will lower when in reverse
Air bag light on
check engine light

Abservations:

spare tire well had a puddle of water in it. I dried it out but cannot find the source. there is small white hose leading from the inside of the rear finder well that is not connected at one end and upon further inspection the open end appears to be bellowed as if it belongs somewhere only i cannot seem to find out where.

occasionally some moisture can be found near the top of the positive battery connection. Cannot seem to determine the source.

Key fob worked just fine as a matter of face has a brand new battery and lights up but doesnt opperate the locks

DOES ANYONE HAVE ANY IDEA OR SIMILAR EXPERIENCES SO AS TO POINT ME IN THE RIGHT DIRECTION? THANKS
 
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#2 · (Edited)
the light problem has a 99.9% chance of being a bad chip in your Light Control Module (LCM or LKM).


you have two options

1) replace the LCM with a new/used unit and have it coded (note: only someone with extensive BMW software tools can code a used LCM, and the dealer will NOT code a used unit).

2) replace the transistor chip that has gone bad - this involves sourcing the said chip, de-soldering it, then re-soldering the new chip.





the moisture is probably bad tail light seals. it could also be any number of drains - roof, sunroof, etc. etc.


the passenger side mirror dipping down is SUPPOSED to happen, so you can see the curb as you parallel park. don't like it? flip the mirror selector switch and it'll stop.



airbag light: have the car scanned with a BMW-specific software/hardware interface:

Carsoft
PAsoft
Peake (not the regular peake, but the one that does SRS)
GT1/DIS
INPA

check engine light: see airbag light - we can't help without you having the codes read.
 
#4 ·
Light Control Module (LCM or LKM).
To the OP, go to the VERY best of E39 Links and do your typical 5-second slash-F3 for "LCM".

You'll find in seconds more than you ever wanted to know about the LCM repairs available to you.

bad tail light seals. it could also be any number of drains - roof, sunroof, etc. etc.
Go to the VERY best of E39 Links and look at these threads:
- How to repair & reset the sunroof (1) (2) (3) & how to fix sun roof rattles (1) & how to test & fix moonroof leaks (1) (2) (3) causing water on the front passenger carpet & how to remove the roof headliner (1)

mirror dipping down
Go to the VERY best of E39 Links and look at this thread:
- Why does my passenger side sideview mirror tilt down when the car is in reverse and how do I stop it?

airbag light: have the car scanned with a BMW-specific software/hardware interface
This is getting repetitive, but, to the OP, do a slash-F3 for "srs" in the VERY best of E39 Links and look at the results. Here's just one result:
- What can cause an SRS airbag light (1) (2) (3) (4) (5) (6) & what tools reset the fault (1) (2) (3) (4)

check engine light: ... we can't help without you having the codes read.
You can read the codes for free, or, for $25 bucks (and you get to keep the tool!).

Guess where the links are? Yup, in the VERY best of E39 Links.

Here's just one set:
- How to identify all BMW computer-specific OBDII fault codes (1) & how to better understand the key EPA federal test procedure (FTP) concept of the BMW "drive cycle" (1) & how to diagnose a typical BMW E39 engine misfire (1) or a sporadic-temperature-change cold-engine intermittent misfire (1) obtaining the pending or diagnostic trouble code (DTC) using free or freeware scans (1) [except in California or Hawaii (1) (2)] or the cheapest ODII scanner in the world (1) (2) or a better overall scanner (1) or the best diagnostic tools (1) (2) (3)

If I purchase a new LCM and install it will it need "coding"?
I didn't think this thread, opened today, would be useful so soon:
- What is the definitive list of E39 modules which, when replaced, need to be 'coded'?

And yes, it's already in the VERY best of E39 Links. :)
 
#5 ·
more information

guys.... I had originally suspected the ignition switch because the symptoms were originally more along those lines however the symptoms have evolved to where they are currently...as described in the initial question. The original symptoms were intermitant and included the key fob not functioning, eratic horn function, turn indicators worked on the outside not inside, dash lights went out ocassionally, radio functioned when it wanted too and even then sometimes worked intermitantly now my passenger side brihjt light is constantly on and key fob still wont operate, however i had the alarm go off accidentally but the key fob was able to turn it off.

So now does this still lead down the same road for repair? LCM?
 
#6 ·
None of the LCM threads lead me to believe that my key fob and high beam staying on all the time can be solved with the LCM fix. can anyone please confirm that they are not related even though they happen to malfunction concurrently? Seems a little simple to assume but this car has odd behavior. Thanks
 
#10 ·
None of the LCM threads lead me to believe that my key fob and high beam staying on all the time can be solved with the LCM fix.
Since you read most of the LCM threads, can you put together a list of the best ones for a DIY?
 
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