I have an 02 Express 3500 with a 5.7 Vortec that will not start. The fuel pump will not cycle when the key is in the on or crank positions. I can command the fuel pump on via my scan tool, and it will run until commanded off. Looking at the wiring schematic, it appears as if the only thing left would be the PCM, or something in the ignition not supplying a signal to the PCM to command the relay on. Any help will be greatly appreciated

 

would you mind snapping a pic of the schematic for me please?

 

For the pcm?

 

fuel pump. nevermind found it and it's not very helpful

 

1. are there any trouble codes set?
2. do you have an aftermarket antitheft device installed?
3. does the ignition signal work? (all lights come up on dash?)

 

1. No, scan tool did not see any stored
2. No
3. I believe so, I will double check this morning

 

Only the abs and seatbelt lights come on when the ignition is switched to on. If I jump the fuel pump solenoid and manually power the pump while cranking, the vehicle will not fire either.

 

yeah it's starting to sound like bad PCM

 

That's kinda what I was leaning towards. Not exactly sure what lights came on normally, my 97 k1500 vortec has check gauges, a battery symbol, and a brake light in addition to the abs that illuminate during the initial key on test. If the ignition switch was bad, I suppose nothing would illuminate?

 

that would be my guess.

Since it wasn't mentioned yet, and its a quick job, you should test all the fuses