Firewall Connector

[Len69Coupe 33]

I have some bare wires very near the square firewall connector next to the master cylinder. One of them (brown wire) goes from there to the starter relay and is giving me high resistance. Does this connector just disconnect from the wall or do I need to remove something on the inside fo the car? Can I replace the wires coming out of it? It's crazy how many bare/rough/stripped wires I'm finding on this car.

 

On another note, my washer pump problem, was solved with a new wiper switch:clap: Still fighting the inop turn signal problem though.

 

Check out the photo from when I first brought the car home. I was troubleshooting wires and decided to eliminate the "wires to nowhere". Well, I got to looking at the silver box (circled) on the side and after some wire tie cutting and exploring found that this box did absolutely nothing. The 2 harnesses coming from it were plugged into each other. It was not plugged into anything on the car. WTF! I removed it and had a bit of a laugh. I know I had one of those on an old Ford truck. I think it was some type of ignition box. Why it was on the Mustang??? I will never know :scared:

[S code 69 13]

There is a bolt in the center of the connector that you have to take out from inside the car, then it will pull apart.

[foothilltom 33]

I can totally relate to your experience with mystery wiring. These 40 year old cars are like little time-capsules with a rich history of good and awful repairs along the way. That little ignition booster system you removed was probably some kid's weekend project back in 1973. Fun stuff. Except wiring problems...those suck.

 

tom

[danno 128]

The box you removed was a Ford Solid state ignition module used from about 1978 to 1990 in almost all Fords. There were different versions of it, but it was used with an electronic pickup in the distributor instead of points in the distributor. I am using one in my car to replace the points for electronic ignition.

 

Bare wires are sometimes difficult to replace. The reason they are bare is often from overheating because something was connected wrong. The wire acts like a fuse and heats up, melting the insulation. Can you see a color on the wires or where they go?

[Len69Coupe 33]

Thanks for the info. The wifey had a disc removed from her neck the other day and taking care of her has really cut into my troubleshooting time, lol! She's getting better, so enough of her and back to the Mustang. lol!

 

I was able to remove the firewall connector and fix a couple of the wires. There was a green/black wire that ran to the headlights that was bare on one side. I also found a broken wire (black) going to the quick disconnect for the right front parking light. Parking light still worked though. Kinda of weird.

 

But, this still has done nothing for my original problem of the turn signals not working. Brief recap - replaced switch, no luck. Blue wire that has power coming into the switch has power until I turn the turn signal on, then power drops off. The blue wire is orange/yellow on the other side of the flasher and comes from a common point. All other items that run on the common point seem to work fine. Any ideas where I should go from here?

 

Another issue I noticed is that there is a pink wiring coming from the ignition switch that goes to the coil and and the starter relay. With the ignition on this wire is getting pretty hot. Not so hot I can't touch it though. I read this is a resistance wire, does that mean it should get hot?

[foothilltom 33]

A hot/warm wire is not normal and should be investigated, if you axe me. It either means there is a high-resistance short or the wire is undersized for the current being drawn. I'd verify that this pink jobber is wired properly by consulting your wiring diagram.

 

Given your various mysteries, I'd not ignore this kind of stuff.

 

Sorry to hear about your wife! Man, a disc removed! Jeez.

[Len69Coupe 33]

The pink wire is a thickly insulated wire that has about the same amount of actual wire as 16 ga wire. It also doesn't have copper wire, it's a silver wire. At some point the PO used a butt connector and replaced the last 12 inches of wire going into coil with regular 16 or 18 gauge wire. I thought maybe the different type wire was the cause, but the wire on that side (coil side) of the quick-disconnect doesn't get warm at all. If it was standard wire I would try to replace it, but since it's "resistance" wire I'm not sure if it would screw something up.

[Len69Coupe 33]

I unwrapped the harness tape that covered the pink wire portion above the radio and found a black wire that comes from the gauge connector not connected to anything. The black wire comes out of the same hole as a purple wire on the gauge connector and is labled on the schematic as "constant". If I read the schematic correctly the black wire is the "blind circuit" on the schematic. What in the world is a blind circuit? The purple and black wires read 11.10 with ignition off and 11.50 with the ignition on.

[69RavenConv 286]

The pink wire is the resitor wire to the coil and you want to keep that if you're running a stock (6V) coil. For the turn signals, make sure you've got a good ground at the bulbs, especially in the trunk. I believe there is a ground wire that comes off each bulb socket that screws to the trunk floor near the filler neck. Without a good ground, I've seen the turn signals act squirrelly.

[Len69Coupe 33]

Thanks Raven, I will look at the bulbs to see if they individual grounds.

 

Any ideas on why the resistor wire to the coil is getting hot? I've checked and nothing that I see is wired wrong, on that part of the car anyway, lol. Would a bad coil make the wire draw to much current making it hot? The car runs with no problems, so I'm just taking a stab at that. Another thought I had was I've been feeling this wire with the ignition on and the car not running. I'm going to reinstall the gauges and run the car to see if the wire gets hot while running. I know the pink wire provides power and the brown wire provides power, but at different points in the start/run process.

[jmlay 80]

I would expect this resistor wire to get warm but I am not sure how warm. As explained by others this wire is used to drop the voltage to the coil. It drops the voltage with resistance & resistance generates heat. You mentioned the resistor wire was spliced at one end.

[Len69Coupe 33]

It's not so hot that I can't hold it in my hand, just worrisome. The resistor wire runs to the quick disconnect (QD) under the hood. On the ignition side of the QD it's held together with a butt connector about 3 inches from the QD. On the coil side the last 12 inches has been replaced and is held together with a butt connector, but the QD side doesn't get warm at all. Makes sense though since that isn't a resistor wire on the coil side. I'm going to reinstall some things tomorrow so I can fire it up and see what the pink wire does whiel the engine is running. I'm also going to measure the current at the coil and see what I have.

 

I ordered the pro wiring diagram yesterday. Hopefully it will shed some light where the other version lacks.