Electrical nightmare--HELP!!!!!
 

This is nothing short of an electrical nightmare. I just replaced the under dash wiring harness with a used one purchased from a board member. It installed perfectly. The problem is the old one that I removed was spliced, diced, chopped and probably a whole lot of other related words. The major splices were to the wires going to the ignition switch, which included a splice from the back of the fuse box into the one of the white and red wires. After all was said and done, I tested the lights, heater, radio etc.. Everything worked fine. I went to start the truck and nothing. I have triple checked all connections. Under the hood is another nightmare. To the right of the speedometer cable is four wires, red, blue, brown/white stripe, and black. These four are just chopped off and taped up. Coming off of the bulkhead connector to the right, going to the battery everything looks good, going to the left, I am assuming to the HEI, starter etc is hacked all to hades. Does anyone have any pictures. Most of these wires are not original and are also spray painted black. The only thing that is not stock on this truck is the HEI. Any help getting her started again would be most appreciated. Thanks David

Re: Electrical nightmare--HELP!!!!!
 

http://67-72chevytrucks.com/vboard/s...ad.php?t=30173
Try the wiring diagrams here.

Re: Electrical nightmare--HELP!!!!!
 

Get us a picture if you can of the wires. Is it an automatic?

Re: Electrical nightmare--HELP!!!!!
 

The truck is an automatic and I will try to get some pictures later today.

Re: Electrical nightmare--HELP!!!!!
 

From the wiring diagram it appears as if the red, blue, brown/white and black went to the voltage regulator. Do I need to do anything special with these wires? Here are pictures of the old wiring harness. There are two pictures of the back side of the fuse block. I hope someone can tell by the pictures what was done. There are two white wires and one red spliced together. One of the white wires attached to the back side of the fuse block. There is another picture of a wiring harness that goes to the HEI, starter, temp guage and brake wire that goes to the proportionong valve. I dont think that the wire to the HEI is heavy enough. Also it appears as if a yellow wire went to the starter at some point in time as there is a small piece attached to the purple wire that goes to the starter. I also attached a picture of what the ignition switch conector looked like--all individual wires with female connectors. I don't think that has anything to do with it, but shows how chopped up this harness was. There has to be something missing because the truck started and ran with the chopped up wiring harness. This new one looks perfect and there are zero splices. I think it has to be under the hood. ANy help or ideas are always greatly appreciated as I need to get this thing back on the road. Sorry for being long winded--Thanks David

Re: Electrical nightmare--HELP!!!!!
 

The purple wire should go to your starter. Run a 12 gauge wire from the "IGN Unfused" terminal on your fuse box to your HEI (it's recommended to put a fuse on it, but I didn't). That should get you running. BTW was this truck running when you got it? Does it have an internal or external voltage regulator?

Re: Electrical nightmare--HELP!!!!!
 

Would the HEI wire keep it from turning over? What Size of fuse would you put in the HEI wire? The truck has been running for the past twelve years since I have owned it. It just stopped today after I replaced the underdash harness. Its dinner time here...isn't it like 4:30 a.m. in your neck of the woods?

Re: Electrical nightmare--HELP!!!!!
 

It is an internal voltage regulator, as the alternator was replaced. I am not exactly sure how they made the wiring change from internal to external though??? I appreciate everyones help as it is very difficult being 5000 miles away from a parts store or mechanic.

Re: Electrical nightmare--HELP!!!!!
 

HEI wire will just keep it from cranking. If you have a tester check to see it the purple wire is hot (12v) with the ign switch in the start position. For the correct way to wire an internal reg alt. look for the faq thread here.
http://67-72chevytrucks.com/vboard/s...d.php?t=157669

PS is the neutral safety switch connected and working properly? It should be at the bottom of the steering column under the dash.

Re: Electrical nightmare--HELP!!!!!
 

Thanks! I dont think there is any problem with the voltage reg. Tomorrow morning I am going to run a new wire from the HEI to fuse block. I am also going to check the neutral safety switch as I could have installed one of the plugs in reverse. I will also check the voltage of the purple wire. I will let you know what happens.

Re: Electrical nightmare--HELP!!!!!
 

Good luck with it.

Re: Electrical nightmare--HELP!!!!!
 

Thanks! I have power. I ended up reworking the wiring harness with new wires and double checking the neutral safety switch connectors. Tomorrow I will put everything back together and order a new starter as the one on there is about 18 years old and starting to fall apart. Seriously, pieces of what appears to be a small bushing fell out of it today and the solenoid was loose. Anyway I tightened it all up and it starts and all of the lights etc. work. Thanks for all of the help!

Re: Electrical nightmare--HELP!!!!!
 

No problem, glad to hear it worked out for ya. My problems all seem to be nagging ones that I can't figure out.:(