Q: Warning lights come on after battery replacement

asked by on June 24, 2016

After changing the battery, all was going well. The next day when I started my car, almost all of the warning lights came on (for ex: ECP, ABS, brake, engine, steering). The speedometer didn’t work either. However, the car is running just fine, fortunately. These things do work: windows, wipers & pump, lights, stereo, etc. The dealership technicians told me that there is no communication with any of the modules and that they need to be replaced. They aren’t able to explain why the car is still working and they can’t tell me what is wrong. Before I give them $5k, please give me your diagnosis of the problem, your advice, and if there’s a way I can fix this. Thanks.

Hello. It sounds like the PCM (powertrain control module) and the BCM (body control module) have malfunctioned because of a shortage in the battery system. This could have happened when the battery failed, was removed, or installed. One explanation for why the car is still working is that the PCM and the BCM has not completely failed, which is allowing it to still function. The only way to repair this problem is to replace and reprogram the PCM and the BCM.

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