LS1swap ECU fuel pump control not working, 04 GTO pcm

[EDH]

I have an IS300 with ls1 swap from an 04 GTO. The issue I am having is the fuel pump control in the pcm does not seem to work. It will not prime at key on. Wont kick in when motor is running and does not work with scanner tools either. The signal from pin 9 (green connector) is always 12v (this is what I should expect with a pull up resistor?) and never goes to ground while testing. Any help is appreciated. Tune attached but it is simply stock with rear o2s and VAT removed. Thanks.

[Bayley]

Have you completely re-wired a new separate fuel pump relay, or did you tap into the existing relay wiring?

Most vehicles have a ground-side-switched / low side driver for fuel pump relay control. In non-GM applications, the fuel pump relay COIL is tied to a +12V source on one side (acting as a psuedo pull-up resistor) and then the PCM will switch a path to ground on the other side when the fuel pump is request on. To test this theory out, turn the ignition to on and ground the fuel pump activate line ON THE TOYOTA HARNESS (MAKE SURE THE GM SIDE IS DISCONNECTED!) This should turn the fuel pump on.

Chevrolet was the exception to this technique by using a high side driver for the relay. If you are working within a Chevrolet electrical architecture, it's not a problem but for most other people though, wiring the fuel pump control relay to the Chevy PCM requires some work around.

Option 1: locate the Toyota fuel pump relay, find the coil side that is tied to +12V when the ignition is on. Cut this wire and instead ground it. Wire up the GM PCM to the other side of the coil and this should work.
Relay_1.jpg

Option 2: add a second relay that will switch a ground source when the GM PCM commands the fuel pump on.
Relay_2.jpg

[EDH]

Thanks for the info. I thought it was a low side output. Will give the other a try. Thanks for the help.

[Bayley]

For reference, this is the fuel pump relay diagram for the 2005 Silverado (L33):

FuelPumpRelay.jpg