Here is a stab in the dark. I was having tail and brakelight issues that traced back to bad solder at the connectors on my CPU on the left side of the driver footwell. Replaced the solder at the large harness connections and all is well.

 

Well mine is torched, and looking @ the service manual from Mazda, it says that the wire that is torched is 12V for BTN, whatever that is. It goes on a 15A and 60A fuse, and goes around all relays.

This might be it, it seems like. It comes in from the E wire on the same plug, and is stated there as Panel Lamp Control.

Worth a shot?

 

Not sure what you mean by this. Also, you have a W/B wire in your headlight harness?

 

I don't know, the wire I am talking about is the one marked in red in the attachment.

It is as stated in the post above yours, BTN.

What this means, I dunno :P

 

Ups, sorry, as Chris from Banzai stated to me in a mail, it is white/green, not white/black.

That is the wire that is torched.

 

Here is some info that will help with the repair:

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/headlight-switch-plug-928274/
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/headlight-switch-harness-burn-help-878824/
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/problem-headlight-switch-42081/
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/tail-lights-dont-work-brake-lights-do-870937/

https://www.rx7club.com/2nd-gen-archive-72/heavy-duty-light-switch-operation-how-too-prevent-burnout-164931/

 

So the wire position encircled in Red is the wire which is damaged. If this is so then the wire in that harness ought to be White/Green in color. The W/G wire receives continuous voltage from the 15 amp Illumination fuse.

The Red/Black wire in the harness receives voltage from the White/Green wire when the headlight switch **** is turned on. The R/B wire is connected to the tail lights,parking lights....... and powers these lights.

 

Okay, from that info I got there, it seems that the white/Green is 12V to the parking lights and so on.

So if I put a regular switch and a relay there, I can manually turn on those lights until I get a new switch from the US?

 

^ Yes.

 

Okay, uhm.

I torched some fuse, but I can't find it. There is suddenly no power there.

I admit I used direct ground to test, which was stupid.

Buut, what fuse can that be? The 15A Illu fuse seemed okay. I cant believe I fried the 60A under the hood? :O

 

The Illumination fuse is an example of a fuse which receives constant power and thus is part of the battery buss and all interior buss fuses besides the two circuit breaker fuses is powered up by the 60 amp BTN fuse.

 

I used to remember... What does BTN stand for?

 

Okay, it worked with a 16amp switch. But, i got no gauge lights, what wire do i need to tap into to get those on the same switch?

While im at it, i got both door lights working, but the ign key hole and the room light doesnt work. What are regular spots for these to fail except room fuse?

 

Gauge lights are powered by the Red/Green wire. The interior spot lights (by the rearview mirror) are powered continuously by the Blue/Red wire. Easy thing to do here is to check for voltage on the Blue/Red wire!

EDIT: The largest plug at the CPU, located towards the top of the CPU, has a Green/White wire which provides the ground signal for the door lock cylinder light as well as the ignition key cylinder light. Jumper this wire to ground and see if these lights turn on or not.

 

Headlight switch is toast if the illumination fuse is good and the BTN fuse is good. Well maybe not the switch but the short harness is.

Pull the plug off the headlight switch and see if the white/green wire is toasted or not.

 

Okay, let me see, small recap:

White/green: 12V from 15A fuse
Red/black: ground via lights
Ren/green: Ill lights
Blue/red: Room/spot

All these @ the headlight switch

Green/white: Ign key illu

@ CPU

And, where is the CPU located? Never digged so deep in this car :P Ever..

Should I use the white/green as ground for the illu cable as well? So I can solder it straight into my new switch?

 

CPU is located next to the interior fuse box, it's closer to the door.

White/Green at the harness headlight switch is a voltage wire and not a ground. I think you mean that the W/G wire should power up both the R/B and R/G wires. If this is the case then yes.

Red/Black is not a ground.

Green/White is the ground for the key and door lock illumination.

Blue/Red is the voltage wire for the key and door illumination.

 

Satch:

Red/black is ground, it must be, as long as white/green is 12V, becuase that is the other cable thru the switch going to the lights Same with the red/green then, ground to the illu lights in the dash.

White/green needs ground to test you said, doesnt that make it 12V?

 

So I can connect this to any random ground and it should in theory work? The spot in the roof I mean..

 

No. Look at the picture attached. The R/B or red/black goes TO various light bulbs and those bulbs get their ground from the socket they are attached to via a near by ground point near those bulbs.

If you pull the electrical plug off the light switch, and then with a spare piece of wire bare at each end, jumper the W/G to the R/B............all those light bulbs the R/B is attached to will light up. Proving there is nothing wrong on that side of the circuit.

 

There are two wires connected to the small bulb found in the door lock cylinder and the ignition key cylinder. One wire has voltage while the other is a ground. The voltage wire is Blue/Red and the ground is Green/White. This circuit is not related to the headlight switch in any way shape or form.

In the headlight switch which is unrelated to the two small bulbs above, there is a W/G wire that provides the voltage to the switch. When the **** of the switch is turned the voltage on the W/G wire is then passed onto both the R/B wire so the tail lights come on and the R/G wire also receives power so the gauge and dash lights turn on. Any light that turns on because the R/B and R/G wire has voltage also has there own ground source connected to the light bulb so it illuminates properly.

 

Well, in theory then, it goes from the switch, to the bulb, then to the ground, so in a way, I was right ^^,

Quick EDIT: That is, from my view point of the switch, if you see it from the bulbs, you get 12V from the switch, and ground from the chassis.



But, my question remains, the roof spot, is that the red/green wire, and can I connect it to any random ground and make it work then?

 

The spot receives voltage via the Blue/Red wire! The ground for that light comes from the selector switch at the spot light. We've been through this at least two times already. The selector switch at the spot light dictates whether the light has a ground or not to complete the circuit. One switch position prevents the ground source from reaching the bulb so it stays off regardless of whether the door is open or not. A second position supplies the ground at all times thus forcing the light to stay on and the last position causes the ground to be supplied only when the door is open. Again, the only two wires involved are the power wire which is constant voltage and that would be the Blue/Red wire and the other wire is Green/White which is the ground source. The Red/Green wire is not related to the interior spot light but is related to the dash lights via the headlight switch.

 

Yeah I got that, but the problem is, where is this Blue/red wire? There are none in the headlight switch AREA at all.

So unless you forgot to say it is somewhere else, there is some different color coding on my car.

 

If the interior spot light is not related to the headlight switch then why would you expect to find a Blue/Red wire at the headlight switch?????????????????

The answer is there is no Blue/Red wire at the headlight switch.

The Blue/Red wire which supplies voltage to the interior spot light is found............. at the interior spot light!