Buzzz

Ok, so I just put a new engine wiring harness in my 72, 350, auto, a/c and now its dead! The only thing that works is the horn. I have studied the assembly manual and read countless threads and I can't figure it out. There is power to the red wire that goes on the driver fender well and the purple wire on the starter and that's it. Any suggestions would be greatly appreciated.

bobs77vet

do you have a 12v light circuit tester? if so start checking the fuse panel to see where you have power.

i think you should look first at the fusible link connection that goes from the eng wiring harness to the starter side of the solenoid. if that melted it would not let the engine crank when you turn the key

Buzzz

Fusible link looks fine, tester shows there is no power to the fuse box, nothing on the car works but the horn. Before I changed the harness everything but the backup lights and gauges worked.

bobs77vet

ok go from the solenoid connection that the main battery lug is on and follow that connection back to where it meets with the main wiring harness. make sure those connections are clean. i am not sure why your horn is working though???? although i dont think that goes through the igntion switch. how about lights do they work? did you disconnect any grounds before you did this?( although i dont think that is your problem if the horn works)

the testing proceedure would be to trace that wire from the main solenoid battery lug back to the fuse box and make sure that the connections where it mates with other harnesses or fuse panel that it hasnt melted or become disconnected. use the 12v probe light and keep tracing and checking at each connection.

Buzzz

I removed both harness from the fuse block and tested with a 12 volt test light. I have 1 live wire on the engine harness and one on the light harness. The engine one is the purple from the large solenoid post I believe. The light is a red that goes to the relay on the left fender well. If I ground the red wire , I can hear the relay click. Now I plugged them together and tightened the bolt and tested the fuse box and still all dead. I assume the car gets its master power for accessories, starting etc. from the purple wire? What should I look for on the fuse box to determine why it does not carry threw?

Buzzz

anyone........anyone at all?

lvmyvt76

Check all the leads are on correctly, slid on the terminals correctly, all safety switches are working, battery is charged up to turn motor over and cables are tight on the battery.

Sonny71

?? connection on the firewall to the fuse box--bad clips or ground

bobs77vet

that fuse box sure sounds like the problem....look for the obvious of broken metal components, maybe the metal connections inside the fuse panel have either broken or rusted away.
you could make a make shift fuse panel of a couple of circuits and run you power supply into it and with it fused bring power back to the fuse panel and test the different circuits. this may alleviate some concerns since you would know that you have isolated the failure to one component.

mev

I'm new to this forum and I'm jumping into the middle of this discussion so forgive me if I'm stating the obvious. (I'm also installing new harnesses and have questions...) However, I may be able to help with the BAT and starter SOLENOID circuits.

First verify your ground connections. If you have bad grounds nothing will work.

If you look a the wiring diagram you'll see that everything on the BAT circuit is connected, unswitched, to the positive battery terminal and should show 12V with the key out of the ignition. 12V should show at the "junction block" on the wheel well and the TAIL, HAZ, & CLK bus on the fuse box. And if you have access, 12V should show on both leads to the ammeter and the red wire to the starter switch on top of the steering column in back of the dash.

When you turn the key to START the SOLENOID circuit is energized. It contains several components. Two are in the engine compartment and two are on the other side of the firewall. The SOLENOID circuit in the engine compartment includes the solenoid and a "starter interlock override switch." (I hope this is part of your problem.) If this switch is not on your old harness, the SOLENOID circuit wires at this point were jumped, i.e. connected together. You'll have to either jump the wires together or get the switch. Check the wiring diagram, the wires are LT/GRN and PPL.

Let me know if that does/does_not get it started.

Thanks

MeV