Rear blinker/brake light wiring
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
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Rear blinker/brake light wiring
I’ve found I have a short somewhere down the line on the driver side blinker/brake wire (the yellow one) because the driver side of the third brake light and the driver side tail brake/ blinker isn’t working. I’m just trying to find some information on the route the wire takes. I found a bundle going to the back in the passenger side floor going all the way back down the side of the car there is a yellow wire in there. Just going to make sure I got the right bundle before I start testing the wires.
Team Owner
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You didn't mention the year BUT your reference to the 'third brake light' is no where near correct. The 'third brake light' CHMSL uses none of the left/right for display. The CHMSL is actually a circuit of it's own. Correct diagnostics would be year and also model sensitive.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
Last edited by WVZR-1; Jun 14, 2023 at 03:41 PM.
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
Likes: 1
You didn't mention the year BUT your reference to the 'third brake light' is no where near correct. The 'third brake light' CHMSL uses none of the left/right for display. The CHMSL is actually a circuit of it's own. Correct diagnostics would be year and also model sensitive.
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
Likes: 1
You didn't mention the year BUT your reference to the 'third brake light' is no where near correct. The 'third brake light' CHMSL uses none of the left/right for display. The CHMSL is actually a circuit of it's own. Correct diagnostics would be year and also model sensitive.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
Likes: 1
You didn't mention the year BUT your reference to the 'third brake light' is no where near correct. The 'third brake light' CHMSL uses none of the left/right for display. The CHMSL is actually a circuit of it's own. Correct diagnostics would be year and also model sensitive.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
***I believe I've seen you mention '85 and if that's correct there was no CHMSL - Added to '86 model year production.
*** Yellow is a GM default for left side signal/stop/hazard.
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
Likes: 1
The CHMSL only has 2 wires. It has 4 bulbs. Seems like the LH two bulbs are inoperative. (It is either all or none. There is no 'left' and 'right' half of the CHMSL.) If the CHMSL is connected to the green wire, then the CHMSL flashes with the right turn signal. Have you ever checked if this is so?
The CHMSL can be wired to the white wire at the brake light switch. Then it would function as a brake light. And all 4 sections will illuminate when the bulbs are replaced. You'd have to run a wire, though.
The CHMSL can be wired to the white wire at the brake light switch. Then it would function as a brake light. And all 4 sections will illuminate when the bulbs are replaced. You'd have to run a wire, though.
Thread Starter
Heel & Toe
Joined: Jan 2023
Posts: 19
Likes: 1
No power to the yellow wire at this location (under the steering column by the switch) I thought this was the problem because the wire was disconnected but it wasn’t.
This connector looks to be going to the fuse panel I could be wrong
This is the same connector other side
The loom going to the back of the car (passenger side floor board)
The splice into the green wire for the CHMSL
The other splice into the ground for the CHMSL
