Saturday, May 13, 2006

Tip#21: No check engine light on 93 BMWs

If you have a short in your vehicle electronics system, scanning for the fault codes maybe impossible because the check engine light will not come on. So what is the meaning of this for you? It means if your engine has a failure electrically, you cannot access or retrieve the codes.


When you use either method like putting a jumper wire to the diagnostic connector or hooking up a generic scanner, the dash light does not blink or the scanner does not work.

Basic Concept:

In a typical BMW vehicle computer system, there are a few control modules involved. These are transmission module, abs module, engine control module, AC module, steering module, air bag module, etc. If one of them is shorted, then the rest cannot be contacted by the scanner. What to do? Here are some tricks you can do so you can make the car’s computer come alive again:

1. Try disconnecting both positive and negative battery terminals and touch them together for at least 60 seconds. Doing this will reset the codes if the problem is not serious.

2. Hook up the jumper wire to the diagnostic connector or your scanner. If it does not communicate, try disconnecting the module one at a time. Watch the result while doing this until the scanner or the check engine light blinks. The last module you disconnect where the scanner works is the culprit. Always start with the trany module because it has the highest rate of failure.

Check with your BMW service manual for the modules wiring diagram or contact ATS


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