Yesterday I was trying to solve why my dash vents aren't diverting air correctly. Decided to rip into my dash only to discover all of the actuators are within reach without going so far as nearly removing the entire dash. So I put it back together but now the truck won't start. Pump is not priming at all. I checked fuses and they all looked fine. I'm thinking passlock issues but I don't know... The pump won't even prime. I let it sit for a couple hours and it fired up. Shut it down and no start again. Tried this morning and it's still not starting. Does passlock 2 disable the fuel pump along with injectors? I always thought it was just injectors. My fuel pump has not been acting up at all either but sure seems like a security issue since I was messing around in the dash unplugging things. Remember it ran fine with the cluster out but started acting up when I put it back in. I don't know what triggers passlock...
What year and model are we talking about? Sounds like you may have inadvertently loosened the plug to your BCM, if you have one(98up). It's up in the same area that you were working on. Might want to check the connector to the ignition switch at the base of the steering column, also.
It's an 03. I saw something under the ash tray. Could that be it? I'm not home right now but I plan on going through and checking all the connections when I get back.
Do you know how the fuel pump relay should work? I found constant voltage at terminal 30 but when should terminal 85 or 86 have voltage? I remember finding 12v at 85 or 86 with the key on. I was thinking that's not right because it should only energize the relay during priming. Plus with the circuit energized, I never felt the relay click when I put it back in. I swapped with another relay but no change. There is something I'm missing here. Just don't quite understand where and when I should find voltage.
The BCM sends a signal to the PCM to start the fuel pump if it likes the key and is matched to the PCM. You may have to have a re-learn done on the BCM, but since it is the original one, I think you are ok. With the ignition on 86 and 30 should show B+ (12V). When 85 is grounded by the PCM, after receiving the signal from the BCM, it energizes the coil in the relay which connects 30 to 87 (power to the fuel pump). 87 is the line to the pump, if you apply 12 volts to it the pump will run, with no way to shut it off except removing power from 87. That wire is usually Grey and in the bundle heading back to the tail lights, gauge sender, etc. Some S10's have a fuel pump test lead from the firewall area, not sure where it is on the 03.
If you open the jpeg in a new window it's bigger.