Diagnosing a Minor Disaster

[jor]

I had a minor frying episode yesterday while installing my F-600 cluster but I can't figure out why. The only thing I have noted thus far is my failure to connect one ground wire, the one to the speedo mount. I have attached a photo. The yellow arrow points to the black wire in question which comes out of the plug. The red and green arrows point to the mounting screws for this wire (splits into two).

Anyhow, after connecting the plugs I was sliding the cluster into place when the sparks flew. I have repaired the damage but am reticent to proceed until I figure out what happened. The black wire in the photo melted partially and a red wire melted all the way from the cluster plug to the starter solonoid. Ouch!

Ideas? Help? Criticism (remember, I have feelings too).
jor

[FORDification]

So this was the panel's maiden voyage or did you just have it out for servicing after being previously installed?

If it's a first time installation: did your truck come with full-instrumentation or idiot lights? The red wire you're talking about is the one between the starter solenoid and the ammeter, and the trucks equipped with a factory ammeter had a shunt to power it. There are also a couple other minor wiring differences between the idiot-light harness and a full-instrumentation harness that need to be addressed before installing an ammeter into a harness not set up for it.

[jor]

Actually, this was its maiden voyage and my truck has full instrumentation. I am familiar (thanks to fordification) with the shunt issue and now that you mention it I suppose that could be the problem as I have been using after-market gauges for a long time and have rewired the end of the harness in the votage regulator/alternator area. Could it be this simple? Nah... it acted like a direct short. How about that second ground wire?

BTW, got my T-shirts. Nice goin', Keith.
jor

[FORDification]

While I'm definitely NOT a master electrician, I seriously doubt your unattached ground wire had anything to do with it. You gauges might not have worked with it disconnected, but it certainly wouldn't have caused a meltdown like that.

What changes to the wiring harness did you make for the aftermarket gauges?

[jor]

It's been a long time. I'll have to check and get back. I'm hoping I eliminated the shunt and that's the prob as I have been using a voltage gauge rather than an ampere gauge. Anyhow, I bought a replacement harness from Andreas (here on the site) and plan on getting it all working with my exisiting setup and then installing the new harness once I have it all spiffy.

I intend to do a lot of pondering and head scratching. When something like this happens and I'm trying to figure out what went wrong I really miss smoking!
jor