Frying wire harness,

[RobertEarl_33]

I'm working on my 3rd wiring harness for my 69 Ford p/u, I got to looking at the previous 2 and the issue seems to be coming from the ignition switch, The large yellow wire was the one that was melted on both harnesses. Any ideas what could be causing this?

[basketcase0302]

RobertEarl_33 on Mon Nov 19, 2012 7:10 pm
I'm working on my 3rd wiring harness for my 69 Ford p/u, I got to looking at the previous 2 and the issue seems to be coming from the ignition switch, The large yellow wire was the one that was melted on both harnesses. Any ideas what could be causing this?

I'd put a good voltage-amp meter on the truck once you get it started back up, (starting out at the battery). Sounds like it might have something in the truck pulling too much amperage. First I'd check the cigar lighter as they usually can be a source of shorting out due to the terminal on the back of them.
Stop by the welcome mat when you get a chance and say hi to everyone:
http://www.fordification.com/forum/viewforum.php?f=1

[RobertEarl_33]

Thanks bud, I got to looking today, the problem is coming from the Black-yellow stripe (37A is what it is on the diagram) wire that runs from the ignition switch to the ignition relay, could it be the relay or maybe the wire was crossed up? I will be sure to do that. Thanks for the input.

[basketcase0302]

RobertEarl_33 on Wed Nov 21, 2012 4:52 pm
Thanks bud, I got to looking today, the problem is coming from the Black-yellow stripe (37A is what it is on the diagram) wire that runs from the ignition switch to the ignition relay, could it be the relay or maybe the wire was crossed up? I will be sure to do that. Thanks for the input.

Are you calling the starter solenoid, (Ford calls it the starter relay) the "ignition relay"?
http://www.fordification.com/tech/wirin ... rging2.jpg

[RobertEarl_33]

Yes the Ignition Relay. My appology.

[basketcase0302]

A few things to check would apply to the starter solenoid itself, to make sure it's not pulling too much power. Check to make sure it's grounded well to the fender / check the ground strap from the intake manifold to the firewall / ground cable from battery to engine / check and clean all your positive battery connections at the solenoid / positive battery connection at the starter itself / make sure the starter itself is clean and bolted solidly to the bellhousing. And I'd also pull the ignition switch out, (after unhooking the battery cable) and check the integrity of the harness on the back of the switch. Make sure there are no loose wires there as loose wiring connections tend to pull more amperage and can melt wiring in a heartbeat.
Has this happened at any particular time-like when cranking the truck or driving the truck?

[RobertEarl_33]

It was while the truck was running and had been for several minutes before this happened, I had rebuilt the engine and took the front clip apart and put it back together. Could it be more of a ground problem than the Ignition Relay itself?

[basketcase0302]

RobertEarl_33 on Fri Nov 23, 2012 12:08 am
It was while the truck was running and had been for several minutes before this happened, I had rebuilt the engine and took the front clip apart and put it back together. Could it be more of a ground problem than the Ignition Relay itself?

I'd assumed that this happened when cranking the truck, I would say otherwise now. Wire 37A would be the main power supply to your fuse panel here, (via wire#37). Maybe time to put a digital volt/amp meter on the truck. I'd first start with the headlights to see if they are pulling too much amperage, (our trucks are known for issues with the headlights due to folks putting in halogen bulbs-where the existing wiring won't handle it). If you don't have access to a digital volt/amp meter you can simply pull the fuses one at a time in an attempt to rule out what is puling too much power. Maybe someone else can pipe in here that might have another idea on what else could cause this too as I'd be at a loss once you've checked all the circuits with an amp meter.

[RobertEarl_33]

Okay, I've got a meter and probably gonna try to do some troubleshooting this weekend on it. As far as the headlights go, it's still the stock set up, no "upgrades" have been done to any of the wiring. I'm wondering if it may be a connection issue because the "burn" stopped at the plug in that comes through the fire wall, and didn't go passed it. Hopefully it's an easy fix.