1978 c10 firewall bulkhead wiring questions
 

Back when I pulled the big block out of this truck I thought I would remember everything and figured the LS would be going in, in a couple months. Well here we are 2 years later and Im just barely doing the wiring on it, of course I didn't label anything. Can y'all help me out with this? Starting at the bottom of the bulkhead I have a tan and a dark blue wire, do I still need these for my 5.3 4L60E swap? Going up next I have a brown wire that use to go to the alternator, do I still need it? Directly to the left wire I have a heavier gauge red wire that use to go to the alternator. Next I have a purple wire, pretty sure that's going to go to the 5.3 starter. Directly to the right of that I have a light blue wire almost see through, not sure what that one is for? And the last one is a heavier gauge white wire, looks like it was feeding the distributor or coil, can I use this for 12 volts ignition source? Any help greatly appreciated.

Re: 1978 c10 firewall bulkhead wiring questions
 

Here are some pictures

Re: 1978 c10 firewall bulkhead wiring questions
 

I wrote up a thread on how I hooked up my PSI Wiring harness - it would technically apply to any LS harness pretty much.

Thread is here
http://67-72chevytrucks.com/vboard/s...d.php?t=797509


I also attached an image that explains what each wire needs.

The one that has power on crank is what I fed switched power to my PCM and fuel pump from - that way the PCM and fuel pump has power while the engine is cranking. This wire in the bulkhead used to feed the coil/distributor.

I used the battery cables from my donor vehicle, and I didn't care about having the battery light on the dash, so I didn't need the bulkhead alternator connector.


Hopefully thats helpful or at least gets a start!

Re: 1978 c10 firewall bulkhead wiring questions
 

It sure does help Eric, thank you brother.