LS swap - fuel pump relay not turning on

[derekf]

Hello, I am using a 2000 PCM with an interior harness/BCM that's either a 99 or a 01-02 (there were a couple of wires that didn't line up with the 2000 service manual so I don't think it's a 2000 body harness). I've also incorporated the LSx steering column so I do have the VATS.

Everything seems to work, except the fuel pump relay.

There is no power coming in on the dark green/white wire at A8 (relay pin 85). If I manually provide power to this wire then the pump turns on and does the things it's supposed to be doing.

I would *assume* (which is never a good idea) that the BCM isn't happy with the VATS, except that the Security light turns off and the engine is willing to turn over with the key.

I do not think I have voltage on the dark blue wire at C3 D8 from the BCM (checked at the blue C230 connector) but one place on the Internet says it's pwm, one says it's to ground to enable the fuel pump. The 2000 service manual seems to think it's both - some manner of PWM ground.

How to troubleshoot this?

I have:

• Voltmeter
• EFILive
• Power Probe
• (maybe) an oscilloscope

My preference would be to leave the antitheft stuff intact but if I've missed a trick with the mix-and-match PCM/BCM then I suppose I'd be ok with disabling.

[derekf]

So if EFILive commanded "fuel pump on", still nothing happened.

A bit of tracing through found that one of the pins in C101 had come loose in the connector and wasn't making contact with the ECU wire. Correcting that fixed the issue. Guess the BCM is fine and happy.

[andrewb70]

Pin 85 would be ground...is the ECU pulling that pin to ground?

Andrew

[derekf]

86 ground, even if the schematic is drawn weird.

And it works, which was really the point I cared about.