Wiring harness/fuel pump
 

Hey guys im trying to finish up 5.3 swap in my 69. Its a 5.3 out of an 04 Avalanche. I sent the harness off to be stripped and cleaned up. I have 2 relays. One labeled main and one for my fuel pump. My question is my fuel pump relay has a green and white wire that comes out of the ecm plugged in where u would put a 12v key switch wire. And the main relay has a key switch plugged into the same spot. My problem is the fuel pump has no switch power to trigger the relay. Is the green/white wire correct and i just have something hooked up wrong somewhere else? Or are my relays possibly wired up wrong by mistake.
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Re: Wiring harness/fuel pump
 

I just reworked my harness, and if memory serves me, the green/white wire is correct from the ecm. The relay should have a 12v+ battery power source to one side of the relay, and the wire to the fuel pump coming out the other.

Re: Wiring harness/fuel pump
 

The ECM provides the switched power for the relay, this lets the computer run the fuel pump power and shutoff if there is a catastrophic failure.

You can wire the green and white to a switched 12v, running off the key. This is the "oldschool" way of doing it, and some here have their truck that way, but the computer gives you a simpler and safer solution.

Touch that switched wire to a 12v and see if your fuel pump turns on; if not, you either have a dead pump, or a wiring problem further up on the 12v HOT wire to the pump. If it does, then you have something wired wrong coming off the ecm, or a problem with the ecm.

Re: Wiring harness/fuel pump
 

Why don't you ask they guys that redid your harness?

Re: Wiring harness/fuel pump
 

Thanks guys. I have touched my fuel pump wire straiggt to a battery source and it runs. Ill do some more checking to see if i have any other wires unhooked something like that.
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