Hi All, I have '57 Pontiac SuperChief and I trying to re-run the wiring harness (which was removed when the car was torn down years ago). I'm trying to figure out which wires go through which holes in the firewall and how they are routed. Does anyone happen to have a diagram or pic of the interior firewall to show how wires are running. I have a shop manual but there are no routing instructions, only the electrical schematics. Dave
Here's a couple link for 57 Chevrolet harness. Thought it might be some help: https://www.trifive.com/threads/1957-what-wires-go-through-what-hole-on-the-fire-wall.261460/
Find some electrical device where only a specific plug will go on and see where the various wires go to from there according to the length of the bundled wires. Shouldn't be that hard.
Unless you are going for a 100% factory build, break the bundles up by function. Some harness kits already come like that. Try to use existing holes with grommets of course. My Ford was 4 or 5 small bundles.
That's what I've done. I've bundled the wires. The difficult part is figuring out how they run through the firewall. I have so many cut outs that I'm not sure which ones to use.
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