Ground the PCM

[Pitpig]

Went for my first start today with 5.3 swap homemade harness. Dead with no fuel pump kick on. I imagined the worst, did the harness myself with lt1swap instructions. Read on another sight to ground the pcm case. It fired right up

[Captainfab]

Thanks for the insight.

[clinebarger]

The PCM body doesn't need to be grounded......If it did, You're missing ground connection somewhere.

[LS short box]

I've never grounded the case of the PCM on my LS swaps. But I've never built a harness myself. Always purchased the PCM and harness from the same supplier.

[Pitpig]

Now that I think of it, there were a few stray ground wires not accounted for, but grounding the case fixed it

[mongocanfly]

With a LS swap, the more grounds the merrier...

[truckdude239]

I had to do the same thing on my swap about 300 miles into swap I had lot of run issuses turns out I never bolted the grounds to back of the head and they where touching hit a bump lost ground I felt like an idiot but never went back and ungrounded the pcm

[LS short box]

As said above Ls swaps love good clean grounds. Main ground cable from the battery I run the 00 gauge cable directly to the engine block. Then on each side of the engine block back to the frame. Similar size cable. I try to hide them. If you have any paint on the block make sure you sand down to good metal. Star lock washers help bite into the head bolt holes.

[87chevy.com]

Originally Posted by Pitpig

Now that I think of it, there were a few stray ground wires not accounted for, but grounding the case fixed it

think it masks the problem of a missing ground... more than likely, something that's needing ground is going through a path its not designed for...

if that's the case, your going to be creating problems thats going to be hard to trouble shoot over the web....