Having and issue with my swap, using a reworked factory harness and 411 pcm, have done plenty of these swaps. issue is with key on fuel pump does not prime but can force relay with hp tuners and pump will come on, VATS has been disabled. Using pin 9 on the red connector to pull in relay like every other swap i have done. Have checked all grounds and voltage sources.


Any input would help

Thanks

 

I have a similar issue. Fuel pump relay cycles rapidly and pcm won't communicate with generic scanner. With t.a.c. disconnected fuel pump relay function is normal,pcm communication works, sensor values are credible and engine will light but not run. I have a stock 02 truck harness and had the pcm re flashed by a third party who will remain nameless for the time being. I have checked all power and ground connections but I suspect there is a secret trick such as a connection that is internal to a device I am not using such as a b.c.m.

 

Problem solved, fixed
This is also posted to the HPtuners site. The problem was trusting the engine supplier to provide matched parts. The problem was aggravated by a improperly drawn diagram from Mitchell. The T.P.S. on a 2002 Tahoe is reversed from sensor 1 to sensor 2 (as 1 goes up 2 goes down). A second problem was that the o2 sensors are case grounded. The Easy and cheap fix was to swap the light blue/black and small black/white wires to the T.P.S. and ground the tan/black and tan wires to the o2 sensors.