1redta

I’m trying to help a friend get his 03 Sierra running again. It has been sitting for a year and was going into 4 hi on its own.

We put a new battery in it and when we turn the key to start the engine the starter solenoid doesn’t have power and the fuel pump doesn’t prime.

we put 12 volts to the solenoid and the engine turns over

also, the obd2 port doesn’t communicate with my code reader or hp tuners.


thanks, Art

strutaeng

Check fuses and relays. Do you hear the relays click when you turn the key to on?

Since it's been sitting check for things like rodent damage?

Fullpower

Couple ground wire connections, left side frame, near body mount under drivers foot well area. Remove fasteners, clean up frame and connections, replace and paint. ( That "might" get your fuel pump and 4WD selector both working.
Next, do same for main positive cable to starter solenoid: if it breaks, replace the solenoid ( you'll have to remove starter to replace solenoid, get a good one. ACDelco, or the brazillian ZEN are okay.
Actual ignition SWITCH contacts on steering column can give trouble, but that is usually intermittent, and not an ALWAY malfunction. Possible that neutral safety switch or connector has come loose ?