help please to ID wires/connectors/terminals

[toddspeed]

OK still trying to sort things out on my truck - PO apparently made some wire mods...hoping someone can help explain a few things:

I found this:

terminals (1024x768).jpg

Which had 4 hot wires (only one fused!) running to the rear bumper area. It appears that the PO either added trailer wiring or had something else back there, but the bed is unmolested and doesn't appear to have had a camper or anything other than a bumper hitch. Plus I'm stumped as to why there would be FOUR 12V unfused wires needed for anything to begin with. They were not hooked up to lights on the truck (but there are some other wires tapped in for trailer lights unrelated to these), literally just constant 12V off the hot side of the starter relay and the little box I show in the pic above - Is that box a circuit breaker or just a terminal expansion? Both terminals are hot all the time.

In other unrelated news: I also found an orange wire under the dash above the fuse panel, with a male bullet connector (looks factory) that doesn't have any power regardless of key, and what appears to be the same wire in front of the firewall as a female bullet connector. Neither end is hooked up to anything (thus the lack of power ). Any idea what it is for? (see top arrow in pic below)

wiresweb.jpg

And in that same pic there was a strange connector with black/red? wires that was jumpered (bottom arrow in pic above)...no idea what that's from either and I've scoured the wiring diagrams. It almost seems like it is for the reverse switch...but the lights work and I can't understand why it would be jumpered?

Any ideas oh wise Bumpmasters?

[71PA_Highboy]

Top pic - that is a circuit breaker... No need for fuses...

Bottom Pic, top arrow - Orange wires were for fuel tank gauges - if you had dual tanks this woudl have been where the second tank connected
Bottom pic, bottom arrow - looks like the backup light switch -jumper may be because you have an auto - I have only had manual turcks, so this is a guess.

Good luck.

[toddspeed]

Great info - thanks!

Is there any way to tell the rating on the breaker? Is that stock for our trucks?

[Art]

Great info - thanks!

Is there any way to tell the rating on the breaker? Is that stock for our trucks?

Usually is is written on them somewhere, but may not be readable after many years.

99% sure it is not original, as I have not seen that on any of the 50+ 67-79 trucks I have owned / worked on / taken parts off of.

[68RGR]

Wanted to comment on the wiring in the first photo.

Looks like the red (fused) wire is spliced to the green wire. The blue(?) wire comes off the starter solenoid and connects to one side of the circuit breaker. There is also a blue wire on the other circuit breaker terminal. So, in effect, this blue wire is fused. That leaves the brown wire. It could be that someone added the brown wire later and found the circuit breaker terminal was a convenient place to connect it. It doesn't make sense to me that someone would fuse two wires (blue and red-green) and leave a third one, the brown wire, unprotected. UNLESS, the breaker wasn't sized correctly to carry the loads for both the blue and brown wires. If so, they took a shortcut by not fusing the brown wire. That is not smart. And, it wasn't smart when Ford did it either. See the last paragraph below.

You wrote there were four wires. I can only account for three of them looking at the photo.

Do all of these wires go to the rear bumper area and are all unconnected at that point?

One explanation would be wiring for a travel trailer - Lights, TV, fan, etc.

It's odd that your post came along when it did. Recently, my ignition switch separated and that resulted in the hot (yellow or black/yellow) wire feeding the switch being shorted to ground. It could have been a disaster. I am about to add a circuit breaker (looks identical to the one in the first photo) to my truck to protect the wiring from the battery (positive solenoid terminal) to the ignition switch. I dodged a bullet the first time and I am not going to miss the opportunity to correct the problem now that it was so dramatically brought to my attention.

[toddspeed]

Yikes that was lucky Bill! Good call on adding a breaker. I assume those are self resetting?

Yes 4 12V wires to the rear (it was a spiderweb of ununsed wires back there that were cut off by PO, and I cut them out since they weren't going to anything). I would kinda get the trailer thing if there was a hitch on the truck. At best it had a bumper hitch at one point, but now it's a chrome bumper and I'm adding a Drawtite frame hitch.

And two of the wires were coming off the unprotected hot side...scary. A fourth wire isn't shown in the pic because it had been cut already.

Anyway, it's all gone now and that mystery is solved in that we all agree it was a dumb wiring job.

[Art]

That is not smart. And, it wasn't smart when Ford did it either.

Good call. I did not look close enough to the picture to see the brown unprotected wire.

I too nearly lost a truck to a short in an unprotected factory circuit. Burned a harness and filled the cab with smoke immediately. Fortunately for me, it was switched by the ignition switch. I was very lucky and pulled a battery cable just to be sure. Learned my lesson and installed a fire extinguisher in each of my trucks - good thing I have not needed any of them.

[toddspeed]

Oh I figured out what the bottom pic bottom arrow jumpered wire was. Yesterday when I was removing the headers I saw the brake prop valve, and the PO had disconnected the "out of balance" connector and jumpered it...doesn't seem like the safest thing but since I am going to do the disc swap soon (already have a donor) I won't worry about it.