What is This Wire That Was Tapped Into?

[wrxnofx]

'87 Coupe

Under the carpeting, just in front of the tunnel cover, I found a wire tap going into a brown/white wire. In the picture here I've removed the wire tap already, but you can see the missing slice of insulation.


The wire comes out from under the tunnel cover. Is this for some part of the lighting system?

[wrxnofx]

Maybe I should highlight the wire:


It continues toward the front of the car but goes either under the carpeting or the autoheat console.

[Classic]

Brown/white is usually a switched earth, but I can't help beyond that sorry......have a look at a wiring diagram for your year and see what it feeds.

[wrxnofx]

Well, I've looked in Bentley, and I can't figure out what it could be according to their wiring diagrams.

I find brown/white in the factory anti-theft (my car doesn't have this option):


I find it in the license plate lights, for the wires that go to ground 414 (hilariously, the diagram in Bentley stating ground locations has no 414, but there is no chance the ground wire for the license plate lights travels back through the car interior):


I also find it for the rear windshield wiper (my car doesn't have that option):


Anyone else?

[SpyderMike]

There is a small gauge brown/white going the the parking brake switch.

[SpyderMike]

This is a picture of it would on my car (1985) with carpet removed. It works with the warning light cluster in the dash.

[SpyderMike]

Sorry, here is a better picture:

[wrxnofx]

Thanks, Spyder!!! Now I know what to check to make sure it still works.

I wonder why someone would have tapped into that wire. Obviously, whatever it was, the prerequisite is that the handbrake was on...

[kodioneill]

Originally Posted by wrxnofx

Thanks, Spyder!!! Now I know what to check to make sure it still works.

I wonder why someone would have tapped into that wire. Obviously, whatever it was, the prerequisite is that the handbrake was on...

Possibly for a car alarm.

[wrxnofx]

So, looking at Bentley, there it is:


Hmm, this is still confusing. The parking brake contact switch is part of the handbrake mechanism. So I would expect this wire to run from the handbrake mechanism up to the combination indicator lamp. Why would it be running to the rear of the car?

[SpyderMike]

Follow the line on the schematic...where does it go?

[wrxnofx]

Originally Posted by SpyderMike

Follow the line on the schematic...where does it go?

It goes to the Brake Fluid Level Control Switch. That switch connects to ground 116 in the front of the car, so that switch must be in the front of the car, I would guess under the fluid reservoir.

[gptom]

Both the parking brake switch & the brake fluid master cylinder use the same light on the dash board. That is their common point

[SpyderMike]

What the schematic is saying is the light on the dash will illuminate if either (or both) conditions exist - park brake switch closed to ground and/or brake fluid level switch closed to ground. The park brake switches to ground when it is engaged and the brake fluid switches to ground when the level is low.

[wrxnofx]

That makes sense. Okay, but that still doesn't explain what the brown/white wire in the above pics is. Neither one of the wires to the dashboard light should extend back into the tunnel, right?

[SpyderMike]

Why wouldn't it extend back to through the tunnel? That is where the park brake switch is located. That brown/white wire comes from one of the dash warning light bulb tangs through the tunnel to the parking brake switch and is grounded locally near the park brake handle when the park brake is pulled up. The rest of the wires it is bundled with go forward through the tunnel as well. If you pull back your driver's footwell wood plate, you will see a bunch of wire bundles coming out of the tunnel behind the pedal assy and up through the front bulkhead. They exit just in front left of the Brake Servo. Pull the frunk carpet back and you can see it all. From there many head to the fuse block and the area behind the dash.

[wrxnofx]

Originally Posted by SpyderMike

Why wouldn't it extend back to through the tunnel? That is where the park brake switch is located.

Aha! Okay, that makes sense. I thought the switch was located where the actual handbrake is located. I want to access all of this but I have autoheat and can't take the passenger seat out to remove the autoheat because the car is currently stored up against the wall on the passenger side. The handle of my handbrake pulls off the end, so I need to figure out how it's connected to the shaft (or lack thereof in my case), but as I said I need to remove the autoheat to get at it from what I can gather.

Thanks a million for the information. I continue to learn so much on here from those way more knowledgeable than me.

[SpyderMike]

I only know because I am in the process of rewiring my car. This is a great site for sharing.