Hi Dave,

oh wow didn't know that!! I don't have a neutral safety switch wired. Mostly because because i would rather have control then saftey. Lol

The blue and red. The 1985 had dimmable dash lighting however the 1980 did not have dimmable dash lights. That part of the harness and the headlight switch is from the 1980.

I have pulled all the all the fuses to circuits not in use mostly to prevent any potential issues with a dash full of unused plugs.

Thank you Dave for you're knowledge and information. You have saved me several hours of hunting for answers.

 

Update ~~~~
Well didn't solve the fuel gauge issue. As far as the extra wire plugs behind the dash i am done worrying about it everything works that i need. I did track the wires and plugs and their presumed functions. I will of course share my findings when complete in the hopes to help others as many of you have helped me.

I did check the voltage at the fuel tank sending unit plug while running of course. It wildly fluctuated to the point it wasn't readable. So from the information in this post and other sources it may very well be the voltage regulator behind the instrument panel.

At this point i have wasted 2 days with 70° weather and there is worked to be done with ol'blue. I will keep everyone posted on any further progress.

 

That is the way the IVR works. It should be a steady voltage fluctuation almost like a turnsignal.

The best way to check the gauges is to power everything up with the key in run, engine can be off. Find the wire going to the sending unit or the temp sensor or oil pressure sensor, and disconnect it. Guage should be full scale empty or full. Then take this same wire and ground it to a good ground. The gauge should swing full scale the opposite direction on the scale. If this works, the gauge is working.

 

Hi Dave,

I will certainly try that first light tomorrow. Thank you. I will keep you posted on my progress.

 

We're not worthy! We're not worthy!

Could I trouble you for another picture? I'm not quite sure exactly where we're looking, other than somewhere near the radio. Maybe another picture from the driver's seat, pointing to the location? How far forward from the face of the dash?

 

Hi Karl,

I have Already buttoned up the dash, but this is just a close up of the photo taken from the driver's side of the bench seat through the radio hole. Its right almost directly above the drivers side corner of the glovebox door.


This view is with the dash pad removed looking straight down. Hope this is helpful. Let me know i can try to get you better shots tomorrow.

 

So that ground is on the metal part of the dash frame and not on the firewall it's self.
Now I wounder if I have a ground there as I always thought it was on the firewall.
I will have to check it out but I also know for a fact the tail lights for the 81 F100 both style side & flare side did not have a ground wire that was in the frame harness that went up to that point.
My style side had grounds at each tail light housings to the bed body.

Flare side to the tail light bracket that bolts to the bed sides.
Now because the bed sides are blotted to the wood floor I dont know just how they got grounded? I have a metal ribbed floor from a style side so it is bolted to the trucks frame that is grounder to the battery from the factory.
Dave ----

 

You are supposed to have that ground in 1981. But you are correct, the farthest back it goes is the fuel tank sending units ground

, unless you have a Bronco.

 

According to this, your rear lighting ground was G1004 or G1002. Both of these grounds are listed as frame grounds, not bed grounds.

 

Here are the location descriptions.

 

Hi Dave,

Yes Sir. Its on the brace frame work between the bottom of the seat and the firewall. I wouldn't have seen it without pulling the top dash pad off. It's to the right of the radio opening and down about 2".

I am not sure but a few screws and you can find out. When i put the 1980 wiring harness in i never noticed it. The part of the harness that burn was from the dash to the fuse box to the engine.

The 1980 truck i pulled many parts from, i was told it was a f100 it had a hood ornament that said "explorer" on it. Whether it was a f100 or a f150 i am not sure.

Please let us know what you found out. Very interested in what you find out. I think my front marker lights are two wires too.

i have a centered ground on ol'blue she's a flatbed. Never thought about a wooden bed truck ground situation.

Hope your week goes well.

 

Bottom of the seat? Autocorrect getcha?

 

I guess you were not using an analog meter were you?

It will be a bit before I can move to get up under the dash to see if I have that but at this point I dont see why I would not now that I know where its at LOL
When I took the wiring harness I also took the dash as a whole from the parts truck and right into my truck not touching the harness on the dash.
Dave ----

 

no a digital meter. I find it hard to find anything has improved with digital technology. Music sounds flat, photos lost without power, etc. As far as i see we have lost a great deal with digital technology.

I cant actually recall what parts of the wiring harness i transplanted from the 80 and what i kept from the 85.

G701 i didn't notice when i was feeding wires through the firewall. It doesn't appear to be ever moved?

 

Gonna have to respectfully disagree with ya on that one. I chase sparks for a living. If you want to take my trusty Fluke 87 from me, you will have to pry it from my cold dead hands. It is my go-to meter for nearly all applications.

With that said, there are a few applications where an analog meter shines. For example, reading resistance as you move the arm on a fuel level sender. A digital meter can miss a minor dead spot, but you'll catch it with the needle sweep on an analog meter. Or as previously mentioned, it's ideal for checking the output of an IVR.

On the other hand, there are MANY applications where you should NEVER use an analog meter. Unless you have a special high impedance version, most analog meters pass too much current through the circuit being tested. Testing continuity through a light bulb? No problem. Testing continuity through an airbag squib? Bam! Whoosh!

Working on a delicate circuit? Say you're measuring voltage drop across part of a circuit board. An analog meter can flow enough current to act as a shunt, and skew your readings. You may be right on the problem area, but the meter itself hides the fault. A digital meter flows so little current that it typically doesn't affect the circuit under test.

Digital meters are also the cat's meow for checking a charging system, for example. 13.25 volts is a bit low, but just a smidge higher at 13.75 is about perfect. Most analog meters don't have the resolution to accurately display such a minor difference. I know you can get an expanded scale analog meter for this purpose, but a digital meter does it handily.

Don't get me wrong. I've got several analog meters (I even dabble in fixing up and reselling Simpson 260s), but I only use them for very specific applications. I use a digital meter for the bulk of my work.

Edit: And don't get me started on the recording feature on digital meters. You can record min/max values, instead of having to watch the meter like a hawk to see a rapid flicker. This is especially nice when working by yourself. It sure beats having to be nice to somebody so they'll help you.