High mount brake light low voltage

[baid]

The high mount brake light on my '86 hatchback hasn't worked since I bought it and the brake light comes on in the dash (inside the diagram of a car). I figured I could just change the bulb but I put a new one in and it still didn't work. I took out the short harness that connects directly to the bulb and hook up some leads directly to the battery and the bulb came on nice and bright. I put a stick on the brake pedal and checked the voltage from the connector and it was around 10.5V instead of 12V, which I guess isn't enough to turn the bulb on. The rest of my brake lights and turn signals work great.
I traced the wiring back up to the front to a large connector near the fusebox under the steering column. When I unplug it, none of the rear brake lights work or get power so I think its a good place to check to see if the voltage is low there too.
The problem is that there is like 20 different pins to check on this connector and I have no idea which one is specifically for the high mount brake light. The connector was a bit brown in color and I circled it in red here in this 1989 electrical troubleshooting guide (It didn't seem to have what I was looking for).
I'm wondering if anyone knows how I can determine which pin is for the high mount brake light or knows why it might have low voltage/what I should do. Its my first car and I've been trying to fix it on my own Thanks

[Oldblueaccord]

The high mount brake light on my '86 hatchback hasn't worked since I bought it and the brake light comes on in the dash (inside the diagram of a car). I figured I could just change the bulb but I put a new one in and it still didn't work. I took out the short harness that connects directly to the bulb and hook up some leads directly to the battery and the bulb came on nice and bright. I put a stick on the brake pedal and checked the voltage from the connector and it was around 10.5V instead of 12V, which I guess isn't enough to turn the bulb on. The rest of my brake lights and turn signals work great.
I traced the wiring back up to the front to a large connector near the fusebox under the steering column. When I unplug it, none of the rear brake lights work or get power so I think its a good place to check to see if the voltage is low there too.
The problem is that there is like 20 different pins to check on this connector and I have no idea which one is specifically for the high mount brake light. The connector was a bit brown in color and I circled it in red here in this 1989 electrical troubleshooting guide (It didn't seem to have what I was looking for).
I'm wondering if anyone knows how I can determine which pin is for the high mount brake light or knows why it might have low voltage/what I should do. Its my first car and I've been trying to fix it on my own Thanks

Sounds like you all over it...

Quick answer there should be a diagram of the pin out some place. Maybe the main manual?

Id say your right there is a bad pin or too in there you may have to replace or just by pass the connector with new wire direct.

[baid]

Hey, I watched your youtube video on the valve cover gasket cause thats something I have on my list of stuff to learn how to do (I believe I have a small oil leak from there).

I bought an '86 electrical troubleshooting manual on ebay just now. Its the correct year instead of the '89 PDF I have and I prefer having the physical copies anyways. I think I should be able to figure it out from there.

Sidenote: Did you ever find out where to get a correct gasket for your valve cover? I think in your video you mentioned the one you got was the wrong thickness. Cheers

[ShiRen]

Ain't everything you need to know in the service manual?

https://www.dropbox.com/scl/fo/9q0r9...cijam82ke&dl=0

[baid]

I have the service manual but it just shows how to change the bulb. I think I need the electrical troubleshooting manual to actually see which pin in the connector is for the high mount brake light

[ShiRen]

Well, it looks pretty easy to follow. Very back of the book, connector C502 connects to the light, you can trace it to C320 in the hatch (check that connection). It shouldn't go much further than that, it connects to C311 on the right tail light then C305 on the left tail light. I believe both tail lights stupidly have 2 grn/wht wires, both go to the high mount. There is a schematic on page 25-89 or 889 in the pdf

[Oldblueaccord]

Hey, I watched your youtube video on the valve cover gasket cause thats something I have on my list of stuff to learn how to do (I believe I have a small oil leak from there).

I bought an '86 electrical troubleshooting manual on ebay just now. Its the correct year instead of the '89 PDF I have and I prefer having the physical copies anyways. I think I should be able to figure it out from there.

Sidenote: Did you ever find out where to get a correct gasket for your valve cover? I think in your video you mentioned the one you got was the wrong thickness. Cheers

I just bought another fel pro gasket.

I never addressed it with them directly in email or call.

You could try some of the parts store brands too.