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I own a Fiat Grande Punto. Recently I was told by the authorized auto workshop that the BCM in my car has failed and needs to be fixed.

So i have two questions regarding that -

  1. What is a BCM and what does it do?
  2. They asked me to give them certain code numbers which came with my car manual and are unique to my car to them. They said they needed it to reprogram the BCM. Now is the significance of those code numbers?

Thanks in advance!

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2 Answers 2

up vote 10 down vote accepted

The Body Control Module is a computer which controls many things in your car not directly related to the engine. Instead of large wiring looms en relais and circuits all over the car all the buttons connect to a single computer which in turn turns on the headlights, open the windows, control the central door locking, etc. A good example is the VAGCOM system in Volkswagens and Audi's.

A Body Control Module is almost always specifically programmed to work with a specific car. For example, a BCM of another vehicle will not open the doors when you use your key or remote. Also, when you try to start the engine it checks the number of the key and a number in the Engine Control Unit as a anti-theft mechanism. Your ECU also does this check, but your BCM can do additional checks like locking the doors to prevent the thief from leaving.

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My 2004 Saturn 2004 would not stary on cold mornings. The triple AAA came out and found checked the battery and alternator was just fine.

After being in the shop for quite some time the found it was the body control module. That is the computer brains of the system.

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