Today a customer had called me about his ’07 Malibu. He had the car to the dealer for a no crank, no start problem. The dealer told him that the BCM was the problem, so he authorized the repair for $800.00 dollars. The dealer installed the BCM and called him back to explain that the BCM did not fix the problem. They told him that they wanted to replace the power steering control module because they couldn’t communicate with it and that it would be the the next step for them to repair the car. They wanted to charge another $800.00 dollars to replace the unit, but they couldn’t guarantee it would fix the problem. The customer said not to do anything else to the vehicle and he then had it towed back to his home.
This is when he called me to ask if I could diagnose his car without replacing the power steering control module. I told him that I could find out what the problem is, without replacing anything. He approved my diagnostic time and I came to his home to find out what was wrong. After some preliminary diagnostics, I found no communication with the ABS, the EPS, the Radio, and the PCM control modules. After checking all the fuses and finding 1 of the PCM power fuses missing,I still had no communication with the Tech2 scan tool or between the other modules.
The system stored the common loss of communication DTC’s. B1001, U2100, D1001, U2000, U2127, U2100, U2103 and some BCM, DTC’s as well. Looks like the dealer didn’t finish with their work when setting up the BCM. I started my pinpoint tests and found a voltage drop of 7.2 volts to the PCM. The voltage drop was found at all the other modules that have no communication. I found 4 fuses in the UBEC that show the same voltage drop.
The customer isn’t ready financially to continue to fix the car at this time, due to the amount of money wasted at the dealer. He asked me if I could come back at a later date to finish the job when his bank account recovers from replacing the BCM that wasn’t needed. I told him I could and probably would be able to fix the car without replacing any other modules.The voltage drop is the cause of all his communication problems. It needs to be repaired to restore the proper voltage for the control modules to function.