1994 F350 dash harness connector ID help

[chickenpot]

By chance, could anyone tell me what this connector is for?

Did a complete dash harness swap into my 1993 F350. Donor harness came out of a 1994 F350, 4x4, and assumed auto trans because of the factory jumper across the clutch switch connector. Recipient truck is a 1993 f350 with the ZF5. Besides a few different pin locations on the dash cluster and 3 connectors, everything has been plug and play so far, except for the ground for the cluster illumination I found in a 3 wire plug female plug on the harness that I do not have a male end to. Which leads me to this connector, which is a 5 pin connector (solid red, solid blue, solid white, solid light green, and solid black). The connectors on the original harness has 4 pins, and lacks the small black ground wire. And for the life of me i cannot remember unplugging it when i pulled the dash apart to get the harness out, thankfully it was only about a month. (if it was plugged into anything at all)


Edit Forgot to add pics. Floor harness pic is the original to the truck. They are similar, same except the ground on the one in the truck. I just cannot find what this plugs into

 

[gnathv]

Is that for an electric brake controller? Is it near the center of the dash?

 

[chickenpot]

Is that for an electric brake controller? Is it near the center of the dash?

Yep, dead center in the dash. that would make sense. So for now I'm going to assume i dont need it, take the old 4 pin connector and put the colored wires into it, and try and ground out the black on the dash support. Having a weird ground issue with the cluster where the tach stops working when the hvac controls move from off to anything. I guess i said everything was plug and play in the op, but it just feels like it cause so much stuff actually did "just work"

Edit it's not a black ground it's actually a small brown wire scratch my idea and now I'm searching again for this issue. back to the diagrams

 

[chickenpot]

Uhh.. Hooked the radio up just for S's and G's and now my previous issue is gone, blower works fine alongside the tach. but now, my right turn signal and the dash illumination seem to have combined themselves, hazards work with the headlight switch off, right turn blinks with switch off but blinks the whole dash lighting with it?? what the **.. turn on the marker lights and the right signal stays lit up and no longer responds to the flasher relay. so right turn illuminated any time the headlights are on. am I the only one dumb enough to have attempted to swap like this?

 

[franklin2]

You have a bad ground back at the taillight area. It will be either the socket at the bulb, or possibly the main ground on the firewall behind the radio. Some of the earlier trucks did not ground the rear lighting at the rear bed area, except some of the flare side trucks. Most of them ran a ground wire all the way back up front and it was bolted to a main ground on the firewall behind the radio. They may have changed this location by 1993 or 1994, but look for a main ground coming from the rear of the truck.

What's happening, when you turn the blinkers on, it is sending power back to one of the rear lights. The power goes through the filament of the light, and then it should return on the ground wire. But there is no ground, so it looks for another path back to ground, It finds it by going backwards up the running/taillight wire. It runs backwards up this circuit, runs through the cluster bulbs, and finds the ground for the cluster.

When you turn the running lights on, you have now blocked the path for the blinker circuit to run backwards up the running light circuit. Now the running light circuit power is running back to the rear lights, going through the running light filament, and then it also cannot find a ground to return on. So it searches and tries to find one, this is where all the crazy things come from, bad grounding.

See if you forgot a important ground going to the rear of the truck. I am assuming you didn't mess with anything under the hood. There is a important ground there from the engine block to the firewall. The engine block has two nice large grounds going to it. But the cab is mounted in rubber body mounts. So it needs this important ground from the back of the engine to the firewall. It has some smaller ground jumpers down around the body mounts, but they sit down there and get corroded.

 

[franklin2]

I don't have a nice diagram for your newer truck. But here's a 86 diesel grounding diagram. You can see G105 and G107 are some of the main grounds for the whole truck.

You must be registered for see images attach

 

[franklin2]

Picture in upper left corner shows G105. Remember this is a 1986. Yours may be different.

You must be registered for see images attach

 

[franklin2]

This shows G108.

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[franklin2]

This shows the important G701 behind the radio.

You must be registered for see images attach

 

[chickenpot]

You have a bad ground back at the taillight area. It will be either the socket at the bulb, or possibly the main ground on the firewall behind the radio. Some of the earlier trucks did not ground the rear lighting at the rear bed area, except some of the flare side trucks. Most of them ran a ground wire all the way back up front and it was bolted to a main ground on the firewall behind the radio. They may have changed this location by 1993 or 1994, but look for a main ground coming from the rear of the truck.

What's happening, when you turn the blinkers on, it is sending power back to one of the rear lights. The power goes through the filament of the light, and then it should return on the ground wire. But there is no ground, so it looks for another path back to ground, It finds it by going backwards up the running/taillight wire. It runs backwards up this circuit, runs through the cluster bulbs, and finds the ground for the cluster.

When you turn the running lights on, you have now blocked the path for the blinker circuit to run backwards up the running light circuit. Now the running light circuit power is running back to the rear lights, going through the running light filament, and then it also cannot find a ground to return on. So it searches and tries to find one, this is where all the crazy things come from, bad grounding.

See if you forgot a important ground going to the rear of the truck. I am assuming you didn't mess with anything under the hood. There is a important ground there from the engine block to the firewall. The engine block has two nice large grounds going to it. But the cab is mounted in rubber body mounts. So it needs this important ground from the back of the engine to the firewall. It has some smaller ground jumpers down around the body mounts, but they sit down there and get corroded.

Thank your for the information and diagrams franklin, the back of the truck wiring is a mess, but I'm going to chase grounds going back that way today if i can get it pulled over the pit. Non stock everything back there, custom flatbed on the truck. Total mess, wires hanging everywhere and such.

I cannot for the life of me find any grounds under the dash except for the two that screw to the wall on the pass side door frame under the glovebox. Haynes refers to this as "Ground F, behind bottom of left cowl panel." could someone show me specifically where exactly that is? inside, outside, behind the dash, on the side?? i dont know where this ground is mounted to the chassis.

 

[franklin2]

Thing about grounds, it easy to add your own in a logical manner and make things work. If you wanted to, you could find a common ground wire for the lighting at the back of the truck, tie into that and run a short piece of wire with a ring connector to the frame where you ground it down to shiny metal. Then go up front and make sure you have a good ground from the negative battery terminal to the frame, or you could use a short piece of wire from the engine block to the frame, making sure to grind the frame clean up there also. Then that would make a new complete ground path from the rear lighting to the battery negative.

 

[IDIBRONCO]

Thing about grounds, it easy to add your own in a logical manner and make things work. If you wanted to, you could find a common ground wire for the lighting at the back of the truck, tie into that and run a short piece of wire with a ring connector to the frame where you ground it down to shiny metal. Then go up front and make sure you have a good ground from the negative battery terminal to the frame, or you could use a short piece of wire from the engine block to the frame, making sure to grind the frame clean up there also. Then that would make a new complete ground path from the rear lighting to the battery negative.

Pretty much what I was thinking too.

 

[chickenpot]

Little update. Got all the bulbs changed out on the front end, all the lights work when they're supposed to. I think one of the broken bulbs filament that was hanging there was touching the frame maybe and grounding out? idk. either way it works.

Still having an issue with the Tach though, it seems like it works worse and worse as the engine warms up UNLESS the HVac is on. then it works perfectly. otherwise it kind of bounces around. I wonder if it's the actual pickup having the typical oil soak problem. Not too big of a deal as long as it drives.

 

[XOLATEM]

You have a bad ground back at the taillight area. It will be either the socket at the bulb, or possibly the main ground on the firewall behind the radio.

My golly ...you are sharp...I want you on my team...if I had a team...

Still...chicken is awful fortunate that you guys are so bright, helpful, and willing...diagrams and analysis and the whole shooting match...

I had the same thing with my truck in the beginning...a crazy spider web of wires in the back....I cut it all out and started over...took a while but it works great now. I had to figure out about the black wire but nothing blew when I grounded it.

I am glad that I joined this site. Thanks guys...

 

[franklin2]

Little update. Got all the bulbs changed out on the front end, all the lights work when they're supposed to. I think one of the broken bulbs filament that was hanging there was touching the frame maybe and grounding out? idk. either way it works.

Still having an issue with the Tach though, it seems like it works worse and worse as the engine warms up UNLESS the HVac is on. then it works perfectly. otherwise it kind of bounces around. I wonder if it's the actual pickup having the typical oil soak problem. Not too big of a deal as long as it drives.

Sounds like a grounding problem to the cab. Do you have a decent sized ground wire from the back of the engine to the firewall? It's always left off when engine work is done, and then you get crazy problems like this. Also make sure you haven't painted things up nice on the truck and the paint is interfering with grounding.