Trunk Light

[fgross2006]

I had to add a trunk wire harness back into my old '92 coupe, but the Chilton manual didn't have the wires right. I eventually just used a simple multi-meter to identify which lights were which via on/off voltage.

Here's the video of the work, if it can help.

according to what you did the two lights that are part of the harness are for the license plate lights. The sellers descriptions on ebay said they were for the 3rd eye brake light but I wasn't able to lay the harness out to make sense of it that way.

I see how the license plat lights layout in your video, what I don't get is wheres the switch that turns this light on or off? Theres nothing in the harness that looks like a switch.

[83GLCoupe]

I'll start with the easy question. The switch for the license plate lights is the headlight switch. They come on with the parking lights.

It sounds like the eBay seller doesn't know what he's selling you. The high mount stop light didn't come out until 1986. In the convertibles it would have been mounted on the trunk lid centered nearest the rear window or in the rear most cross rail if it was equipped with a luggage rack. In the coupes, it was mounted inside the rear window on the package tray. So the harnesses for each of the models would probably be different, but I don't have first hand experience with this.

[fgross2006]

I'll start with the easy question. The switch for the license plate lights is the headlight switch. They come on with the parking lights.

It sounds like the eBay seller doesn't know what he's selling you. The high mount stop light didn't come out until 1986. In the convertibles it would have been mounted on the trunk lid centered nearest the rear window or in the rear most cross rail if it was equipped with a luggage rack. In the coupes, it was mounted inside the rear window on the package tray. So the harnesses for each of the models would probably be different, but I don't have first hand experience with this.

I was asking where's the switch for the trunk light, not the licence plate lights.

Trunk light should come on when the trunk is opened. But I don't see a switch anywhere

[83GLCoupe]

Oh ok sorry about that. That was the way I read that post.

In coupes and convertibles, the bulb socket is the switch. There is a single hot wire running to the light assembly. The bracket is the ground. There is a small bubble of mercury inside the socket. When the trunk lid is opened, the mercury rolls to make contact with the bracket to complete the ground circuit and the light comes on. When closed, the mercury rolls away from the contacts breaking the circuit.

In hatches, they have a conventional door jamb type switch that completes the ground circuit when the hatch is opened.

Hope that made sense.

Chris

[fgross2006]

Oh ok sorry about that. That was the way I read that post.

In coupes and convertibles, the bulb socket is the switch. There is a single hot wire running to the light assembly. The bracket is the ground. There is a small bubble of mercury inside the socket. When the trunk lid is opened, the mercury rolls to make contact with the bracket to complete the ground circuit and the light comes on. When closed, the mercury rolls away from the contacts breaking the circuit.

In hatches, they have a conventional door jamb type switch that completes the ground circuit when the hatch is opened.

Hope that made sense.

Chris

Yeah it makes sense. A few people told me there was no actual trunk light switch in the trunk of the verts and coupes. I just found it hard to believe there's mercury in that tiny light fixture but I suppose I'll try and see what it does. I would also imagine for the mercury switch to run right then the light fixture needs to be installed in the exact correct spot with correct orientation. Does anyone have a picture of the trunk light in its installed location? Days of Googling have produced nothing but frustration.

Also, I ended up buying the harness from an FEP member but I was referring to this eBay listing which lists it as wiring for the 3rd eye light.

http://www.ebay.com/itm/87-93-FORD-M...tWHZmH&vxp=mtr

Just to ask,
All the harnesses I saw on eBay looked the same with same connectors. My car has no matching connectors in my trunk wiring. My stock wiring is all wrapped in stock electrical tapping. As luck would have it, my mechanic is stripping down an 88 vert for parts for another customer. That car has the matching connectors in the trunk wiring. should I be able to cut those connectors out of the derelict car and splice them into my existing harness? Will I find corresponding wires with correct colors?

[83GLCoupe]

I looked at that eBay listing and the others that were similar on the bottom of the page and none of those have the wiring for the high mount stop light. That single bulb with the Green-yellow stripe wire is the luggage compartment light. I wish people wouldn't list items incorrectly.

Since your car is an '84, it will not have the right wire connectors for the high mount stop light. It simply wasn't available that year.
To see if the wires would correspond you'd have to compare the 2 years' wiring diagrams. I haven't tried so I couldn't tell you for sure. I think there is another harness that runs from the trunk area to the front left kick panel that you would need too if you don't have the corresponding connector. It's shared with the remote trunk release wire if I recall correctly.
I can't find a picture of the mounted luggage light either. Ask the guy who's stripping the '88 to take a pic if its not too late.

[fgross2006]

I looked at that eBay listing and the others that were similar on the bottom of the page and none of those have the wiring for the high mount stop light. That single bulb with the Green-yellow stripe wire is the luggage compartment light. I wish people wouldn't list items incorrectly.

Since your car is an '84, it will not have the right wire connectors for the high mount stop light. It simply wasn't available that year.
To see if the wires would correspond you'd have to compare the 2 years' wiring diagrams. I haven't tried so I couldn't tell you for sure. I think there is another harness that runs from the trunk area to the front left kick panel that you would need too if you don't have the corresponding connector. It's shared with the remote trunk release wire if I recall correctly.
I can't find a picture of the mounted luggage light either. Ask the guy who's stripping the '88 to take a pic if its not too late.

My car has the 3rd eye light but it was installed not original.

the wiring is hacked into the driver side brake light which I believe has left me with a sometimes faulty driver side brake light.

I asked my mechanic to re-do that as well today so Ill let you know how it goes.

[fgross2006]

Well the mission was not accomplished. The 84 convert trunk harness does not match the 88. The harness I bought has connectors that mine doesn't have matching connectors for.

We pulled the entire brake harness from an 88 thinking we could splice the connectors into my original trunk wiring but after opening the wire wrap we found no matching wire. The wire to the light holder is green. No green wire in my trunk wiring. We checked every wire in the trunk and not one is hot with key off.

It looks like the only way I can do this now is to run a hot wire to the trunk with an inline fuse.

Here's a pic of what my trunk wiring looks like.