02 conv. 2.7 .... Battery light is on, so was CEL. Scanner come back with only O2 sensor on upstream being bad. I replaced alternator(reman) and battery to eliminate possibilities. Same issues. From what I've learned, the voltage reg is built into the pcm. The car runs great until it drains the battery or if you unhook the battery. So my questions are:
1. Is there a way to test to make sure the VR is functioning correctly?
2. Anyone know the cost of the pcm?
3. Does the car have to be reprogrammed with a new pcm?
4. Am I looking at the right problem? (not that I want the pcm as a prob)

Thanks for any insight!

 

Start with a DRB3. But if your battery is being drain because of a draw, you need to fix the draw 1st and test the PCM. And if you end up replacing the PCM, then the controller needs to be program.