mjollnir

I'm wiring my harness on the LQ4 and I have an issue with the PCM

Here is what I did:

PCM (blue connector) pin 1 to negative battery terminal
PCM (blue connector) pin 57 = C2 pin B8 (2 orange wires) receives the perm +12V

Once I put the blue connector into the PCM, my main fuse burns.

Am I doing something wrong?

Harness is from a Silverado 2006

badcoup

try this

mjollnir

my wiring matches ur diagram, i will open the pcm to check for a short

badcoup

double check everything these things can frustrating at times and turns out to be something simple. Do you have an extra pcm to plug in?

mjollnir

I don't have a spare PCM (can't find that easily in Europe )

I just tested again, I only connected big red terminal to battery +, and the black wired terminal to battery -. Then I mesured voltage between pin B7 and B8 of connector C2 (underhood fuseblock), it reads 3.30V. I should have 12V there right?

Some more info: no short circuit between those 2 pins (reads 0.6V when harness power is unplugged) so I guess the PCM has a small battery to keep some settings like date/time when you change your main battery.

I don't know where the short comes from

badcoup

you should have 12v there. sounds like 1 of those wires are grounded somehow. I would run the orange wires together to a fused 12v point directly.

no1kicker

iTrader: (4)

How about using your multimeter on the harness pcm connectors? Pop off the plastic and test for continuity between the batt and ground pins.

mjollnir

No continuity

mjollnir

My fuse burns when I do this

mjollnir

The problem was evident when I opened the PCM:



A few shorts between some pins. Bad design there GM!!
The pins are easily pushed inside the PCM if the connectors are not perfectly aligned and parrallel to the PCM


Pins put back where they're supposed to be



Let's plug the OBD2 now