Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I have a 2002 gmc sierra1500 that fuel pump won’t prime. These are things I’ve done so far. Checked relays and fuses, all good even swap around matching relay and fuse. No go, then checked ohms from harness to about mid way of truck cab and got reading. Cleaned and checked all body and motor grounds. Installed new pump. Did start pump by bypassing relay and using battery power and it pump fuel. Tested and checked ohms on relay fuse box from top and bottom of fuse box. No codes and also did the 30 min key on 15 sec key off repeated twice security relearn. At the same time the truck did this no start symptom the gage cluster stop working don’t know if did is tied together but need help
Today I tested the green with white wire that leads from fuel pump relay at fuse box to pcm at pin#9 and got a reading set at ohms. So scratch that out. We’re is g117 ground located . It’s the fuel pump relay ground.?
Does the Green/White wire, from pin #9 have battery voltage when the key is first turned on and while cranking?
I am seeing fuel pump relay ground as being G105.
Also, be sure to check the ECM B fuse (20a).
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
I tested that pin #9 with harness off computer and battery disconnected. I seen diagrams of that ground numbered g107/g117 /g05 but it all point to ground behind motor.
Update did the Test light on #9 pin with it plug in to ecu and did the key on and no power. Also ECM B fuse is not blown. That ground from pump relay is it going to rear left back of motor or left side of motor? Different diagrams on net that’s y I ask. Gonna recheck these grounds again using ohms meter.
Last edit: 3 years 8 months ago by SC02gmc. Reason: More info missing
To test the relay ground you can run your test light from battery positive to the relay base terminal #86. If it lights up bright your ground is good enough to pull in a relay.
While you're in there it'd also be worth rechecking relay control from the PCM with the test light from terminal #85 to battery negative. It's possible you didn't have pin #9 probed good. If it doesn't come on for a couple seconds when you first turn the key to run try cranking to see if that turns it on. I'd expect your vehicle to have key on prime but I've been wrong before......
