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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 10-01-2013, 11:39 AM
captbob captbob is offline
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Location: South Carolina
 
Join Date: Oct 2013
Posts: 1
Mein Auto: 1992 E30 325ic
Brake Light Issues

Vehicle: 1992 E30 325i Convertible, Automatic (M20)

VIN: WBABB2316NEC29716

Issue: The BRAKE LINING light on the instrument panel and the BRAKE LIGHT on the windscreen check panel flash intermittently.

Background:

The BRAKE LINING light illuminates, as I drive down the road.

The BRAKE LIGHT illuminates, if I maneuver the vehicle suddenly.

Neither illuminates when I step on the brake pedal.

Went to a BMW mechanic, had the brakes checked, and they are good. Mechanic also changed out the bulb in the third brake light. Problem with both lights continues.

I was advised that the problem probably resides in the AT-CONDUCTOR PLATE ("MotherBoard") and or the PRINTED CIRCUIT BOARD. Both are part of the vehicle's instrument cluster, residing inside the dash behind the speedometer and tachometer.

The AT-CONDUCTOR PLATE is a board shaped similar to the instrument panel and sits vertical, while the PRINTED CIRCUIT BOARD has two batteries on it and sits horizontal, plugging into the bottom of the AT-CONDUCTOR PLATE.

There is a second and smaller Printed Circuit Board (it controls the service LED lights) that plugs into the top of the larger PRINTED CIRCUIT BOARD. That part is not in question.

The above parts are available OEM through BMW but are very expensive. They are also available OE repaired through other sources at a far more reasonable price.

One source is Programa Inc. out of Florida. Has anyone purchased rebuilt electronics from this company?

Bottomline:

1. Has anyone else had the problem I'm experiencing with the BRAKE LINING light and or the BRAKE LIGHT?

2. If so, how did you correct it? Did you change out the AT-CONCUCTOR PLATE and or the PRINTED CIRCUIT BOARD?

Thank you and kind regards,
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  #2  
Old 10-01-2013, 04:29 PM
cjmertz cjmertz is offline
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Location: westminster
 
Join Date: Jul 2013
Posts: 62
Mein Auto: 325i
.. intermittent electrical problems are difficult to trace/fix even under the best of circumstances,...they just won't 'fail' on demand.. worse when the only time it fails is when your driving down the road and can't take your eyes safely off the traffic to monitor any test equipment/meters. ., much easier to find a hard fault, like loss of power, or ground,... when it doesn't work at all...

tackle one issue at a time. That way you don't loose track of what your doing, and maybe fix or partially fix/ disrupt/disturb the other issue. Maybe if you aggravated it some the frequency of failure may increase...maybe not...never knowing either way is a certain source of aggravation/frustration and adds to the challenge...


One thing is for sure, guessing at probabilities, starting with the cheapest component whenever expensive circuit boards are involved, gets out of hand quick..

How comfortable are you with a multiimeter? Can you read an electrical schematic?

I can offer 2 cheap maybe's.11) Regarding the brake lining lite, often after several brake pad sensor replacements, the harness will break.., Internally, usually somewhere near the sensor to harness connection...inspect very carefully, pull the harness as if stretching it in several places...if it feels like a rubber-band anywhere in the stretch...you may have found a break...look closer, remove all 4 wheels and inspect each brake sensor harness area in this way..


2) As for the intermittent brake lite, I would just flat replace ALL of the brake bulbs. Don't try to save money here, purchase original equipment bulbs. Now at least the vehicle has a chance to recognize what it's supposed to see thru the circuit boards... and you may sleep better knowing all the bulbs are new and compatible with the vehicles electronics.

Search eBay for an electrical manual....

Good luck!
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  #3  
Old 10-05-2013, 07:28 AM
BMWFatherFigure's Avatar
BMWFatherFigure BMWFatherFigure is offline
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Location: Perth, Western Australia
 
Join Date: Aug 2012
Posts: 1,908
Mein Auto: E23;E30;E38;E32;E34 +
Try changing all the brake light globes. And while you are at it check and clean the contacts. The blown globe sensor sees pitted filaments as blown..
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  #4  
Old 10-06-2013, 04:25 AM
cjmertz cjmertz is offline
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Location: westminster
 
Join Date: Jul 2013
Posts: 62
Mein Auto: 325i
Good point on the pitted bulb/ globe contacts.. often easily over looked.. high resistance plays havoc with the electronics.
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  #5  
Old 10-23-2013, 02:19 PM
dinahbmw325 dinahbmw325 is offline
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Location: 24060
 
Join Date: Sep 2011
Posts: 35
Mein Auto: 1987 325
whats the best way to clean the brake bulb contacts?
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  #6  
Old 10-23-2013, 05:22 PM
cjmertz cjmertz is offline
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Location: westminster
 
Join Date: Jul 2013
Posts: 62
Mein Auto: 325i
..
carefully remove only that part of assembly of the tail lite housing containing the bulbs, ( two plastic thumbscrews) , , accessible from inside ..the trunk... disconnect the body electrical harness from the part of the housing containing the bulbs...
take the assembly to the work bench , under a bright lite remove all bulbs, if the 2 metal contacts on the bottom of the bulbs have rust, or corrosion build-up on them,. Clean contacts with a fine wire brush or 600 grit sandpaper till shiny, set them aside

inspect the receiving end of the bulbs or the bulb 'socket' in the housing clean /remove any big chunks of loose rust or corrosion, with a pocket screwdriver, shine contacts best as possible.. if the bulb socket contacts fall apart while cleaning, toss complete assembly into the trashcan, go to the dealer, bite the bullet and replace next higher or needed assembly. Nothing short of a clean corrosion/rust-free metal-to metal contact surface between bulb and connector should be considered reliable . There ya; go... Pay particular attention to the 2 contact areas between bulb end and contact pin area of the socket, if the barrel of the socket is heavily corroded, and its questionable you have made positive/clean contact when installing the bulb, toss the socket/ housing assy into the trashcan..
p
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