2007 2.2 Ecotec Will Not Start
I was hoping to get some advice as to what might be preventing my 07 from starting. It's actually a 2007 Pontiac G5, but I did not see a place to post this on the G5 section. The car has had this issue intermittently for some odd time and usually starts working after trying to turn the ignition a few times, but now the car has not started for about a month. I don't hear the starter trying to engage, or anything. In the past I would sometimes hear faint clicks from the starter trying to engage, and it would eventually start, but not for the past month.
For the crank circuit I checked and verified that I'm getting a constant 12V on the big terminal on the starter. I checked to see if I was getting the 12V signal to engage the solenoid on the starter when trying to start, but I was getting 0V on the signal wire at the starter. My first thought was maybe a bad ground as many people have mentioned on youtube videos I have watched, so with the battery disconnected I cleaned and checked the grounds G105(transmission ground) and G103(body ground). The resistance I'm seeing on any ground in the engine compartment is about 0.006 OHMS.
After putting the battery back in, the car still did not start so I moved on to checking the voltages at the crank relay in the fuse box under the hood(with the crank relay removed). This is where I get a little lost. From the Autozone wire diagrams it looks to me like I should have 12V as a constant voltage to pin 30, and then 12V going to pin 86 of the starter relay only in start and in run, with the clutch pedal pushed in. So far, this is exactly what I am seeing. But for pin 85 of the starter relay(starter relay control side) I am seeing around 3V in start and in run. I would assume this should be open in run and 0V in start. These voltage measurements were taken with the G103 as a ground reference, and then I used the ground on the strut tower to double check. I assume that a 9V difference between pin 85 and pin 86 is not enough voltage to energize the relay to start the car.
What really confuses me is that in order to complete this circuit in run, it looks like the ECM has to make a decision in order to ground that connection(to pin 85) so I can have 12V supplied to the starter relay coil. I'm not quite sure what conditions the ECM is looking for in order to complete that connection and ground the circuit. Does anyone know? Should I be approaching this issue a different way?
Last edited by internetpimp; 03-30-2018 at 08:08 AM.