I'm going to start off by saying I am a forklift mechanic, so I have some background, i.e. I'm not ignorant
I own a 2003 Chevy Cavalier, 2.2L Ecoboost. I will list the issues, all symptoms, and diagnosis procedures I have used thus far.
The issue is intermittent, but has become a lot more frequent as of late. When I go to start the car, it acts as if there is no fire. Just cranks, that'* all. 9 times out of 10, the DRLs will flash erratically, the fuel pump relay will click on/off erratically, and a loud buzzing sound will come from the fuse box inside the car, (the DRL relay going nuts). If I can hear the fuel pump come on 5 times out of 10, the car will start, and 1 time out of 3, the car will die immediately after it starts. On some occasions, the car will shut off DURING DRIVING, and is a total pain starting again. And it may do that during driving a few times rapid fire, then works fine. I know that if I don't hear the fuel pump come on, it WILL NOT START! At one time, I closed the glove compartment, and the car shut off (lol). The instrument cluster goes crazy as well. When starting the car, all the gauges drop underneath where they normally ride, indicating an electrical issue.
Now for my diagnosing procedures thus far.
I have correct fuel pressure in the system. I'm getting fire. The fuel pump is ok. All relays are good. Engine grounds have been cleaned and reattached. All fuses good. Aftermarket radio has been rewired to ensure no issues there. Checked the harness going to the fuel pump, all ok there.
My thoughts : I strongly suspect the BCM to be the problem. It controls everything that is listed as a symptom. The instrument cluster going nuts also points me in this direction. I'm not sure how to diagnose the BCM, since I'm sure GM is the only one that knows the test points. Does anyone know where to back probe the BCM and the voltages to look for? Are there grounds for the BCM underneath the hood?
I may have missed some things, but feel free to ask questions if further info is needed. Thanks ahead of time for the help!!!
Lately, I've wanted to do this --->
to my car.