72 chevelle electrical problem

[72drop]

Whats up all, im going to try to make this brief. I have a 72 chevelle with a 454. My altenator Shorted against a steel gas line. The hot wire from the back of the altenator the goes to the horn relay was getting super hot. To hot to touch. So i figured that somthing had to be grounded. So i test all the circuits that go to the horn relay. Come to find out that, That the red power wire that powers up the fuse block is grounded. So i pulled the engine harness to make sure it wasnt just a bad connection. It wasnt. the terminal is grounded .Not sure where to go from here And i also noticed that i lost my two inner brake lights are not working. And both bulbs were burnt. I still have blinkers and outer brake lights. Should i pull the fuse panel off ? What can i test? Any advice would be appreciated.

[MrQuick]

Try disconnecting the alternator leads. See if that changes anything.

[72drop]

I have the whole engine harness disconnected, and the terminal that Powers up the fuse is grounded. Can the alternator leads still ground the fuse box?

[MrQuick]

oh ok, hard to read your post. So your harness is out and your still grounded at the 10g bat lead? I don't have my circuit diagram here.

With your test leads at the firewall bulk head to interior, start disconnecting components. Ignition switch, cluster.....

[Chevelle598bb]

The outer lights are brake lights / turn signals and the inners are just back up lights unless you changed them.

I have a 71 which was externally regulated so a bit different than your 72 which was the first year to be internally regulated. Is the main power feed on the bulkhead connector leading inside grounded? If it is then I would look at the ignition switch first and then the headlight switch. That is where the main feed goes after it passes through the firewall.

[72drop]

The outer lights are brake lights / turn signals and the inners are just back up lights unless you changed them.

I have a 71 which was externally regulated so a bit different than your 72 which was the first year to be internally regulated. Is the main power feed on the bulkhead connector leading inside grounded? If it is then I would look at the ignition switch first and then the headlight switch. That is where the main feed goes after it passes through the firewall.

When you say the bulk connector leading inside, Do you mean the hot wire that powers up the fuse board? So i checked the ignition switch by un pluging all harness to the entire steering colunm. then check if that teminal was grounded and it was. Then i checked the headlight switch by taking the switch out and the teminal was still grounded. Not sure where to go from here.

[Chevelle598bb]

What about the feed wire? Is it still grounded? The ignition switch and headlight switch should show that terminal grounded since it is always hot.

[72drop]

What about the feed wire? Is it still grounded? The ignition switch and headlight switch should show that terminal grounded since it is always hot.

Feed wire is the wire the powers up the fuse panel?

[MrQuick]

yes

[Chevelle598bb]

Unhook the headlight and ignition switches. Check the feed wire under dash near the fuse box and check to see if it is grounding. More than likely this is your issue since the alternator power grounded. The main feed wire is connected all under the hood and dash. It only takes a small bit of heat to melt the sheathing off a 40 year old wire that was not very high quality in the first place.

[72drop]

Unhook the headlight and ignition switches. Check the feed wire under dash near the fuse box and check to see if it is grounding. More than likely this is your issue since the alternator power grounded. The main feed wire is connected all under the hood and dash. It only takes a small bit of heat to melt the sheathing off a 40 year old wire that was not very high quality in the first place.

Do I need to pull the fuse panel to access the wire? Thanks for the help. Il keep you updated on problem.

[Chevelle598bb]

No you can leave it in place. I would check the main feed wire on the fuse box from under the hood and then find it where it goes to the ignition switch.

[JEFFTATE]

Uhm , if that wire is completely grounded , like shorted to ground , wouldn't it melt ??? And need to be replaced ?

[Chevelle598bb]

Uhm , if that wire is completely grounded , like shorted to ground , wouldn't it melt ??? And need to be replaced ?

Yep. That's what I think has happened but you can't see the main feed wire if the harness is still in the car and wrapped up. I think the jacket on the wire melted and is shorting to other wire(s) in the harness. More than likely it and a few other wires will need to be replaced.

[72drop]

What is the best way to trace that wire? I removed the engine harness and the terminal is grounded , From inside the car, i dont need to remove the fuse panel? I have never removed one before. what is in the back side of the fuse panel?