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Ekansh Katihar Posted on Feb 20, 2015
Answered by a Fixya Expert

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Indicators, headlight, high beam, Heater showing strange behavior. Can you please suggest what could be the possible reason for it . BCM or Multi Function switch?

My car - Hyundai Elantra 2008 Automatic started showing some weird behaviour List of behaviour initially 1 I have to manually switch off the heater for it to stop working even if I have switched off the car , took out the ignition key and lock the car. 2 If the head lights are on 2.a On giving the left indicator, the indicator light on the dash board doesn't switch on and off but remain in on state only. When I check from outside the left indicator is not working 2.b WHile giving the right indicator the indicator light on the dash board suggests that indicator light is working. However, the right indicator is not working 2 If the head lights are switched off then the indicators work . But then ALL the interior lights also start to flash 3 High beam is not working . List of behaviour after after some hours of driving High beam is not working but dash board is showing high beam and the dash board light for the high beam starts to flicker Can you please suggest what could be the reason behind all this. Would it be because of a body control module BCM and/or multi function switch To give more details I took my car to mechanic and he tried three BCM from junk yard and all of them gave different behaviour. So my mechanic finally changed the BCM and now my car can - heater does switches off when I turn off the car - indicator works as expected and the interior lights do not flicker - He did some patch work by passed some relays and now when I turn on the ignition of the car head lights switches on . So basically if my car is on I cant switch off the head light My cars dash board shows the car is on high beam And, I can't give the high beam.

2 Answers

A

Anonymous

Car companies don't like DIY's so they design more and more parts to make sure you will go to the dealer. Which is the main reason why almost all functions are routed through the BCM. After all why only make $10 off the customer for a light bulb, when you can make $600 by making the BCM fail instead? That being said, BCM's are "matched" to each vehicle both through the VIN and through the Computer (another nice way to keep you from doing it yourself!). In other words 99% of the time the BCM can ONLY be replaced with the identical part, all numbers MUST match or it won't work properly, sometimes not at all. If its the correct one, no bypassing will be required! Assuming of course the BCM is the problem.

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  • Posted on Feb 20, 2015
Jeremy
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Hooking up an OBD2 reader will tell you right away if the BCM is shot or BCM. Take it to advanced auto or O'Riley's they will hook up a an OBD2 reader and tell you. Sounds like a faculty PCM and BCM to me or just faulty PCM since you've replaced the Body Control Module already.

  • Jeremy
    Jeremy Feb 20, 2015

    Your mechanic would know all this though, well a certified mechanic.

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Also check a bad wire between the fuse block and the BCM. before replacing the BCM . Start under the fuse block. This is the fuse block under the hood.
This will help. Thanks please keep updated.please do rate the solution positively .thank you for using fixya

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