3rd Brake Light Issue
Thread Starter
Instructor
Joined: Apr 2008
Posts: 171
Likes: 1
From: west chester pennsylvania
3rd Brake Light Issue
Need to get my 87 inspected this week and the 3rd brake light isnt working. Replaced the bulbs and still nothing. Is there any special grounding or anything needed? Any thoughts?
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The 3rd brake light has a separate wire coming off the brake light switch. It's possible that the switch may not be allowing curent through the wire or the wire is loose.
The brake light switch sits above the brake pedal. The 3rd brake light wire is light blue and is in cavity C of the connector. Depressing the brake sends voltage to the 3rd brake light. Check for 12v at the wire going into the lamp housing.
If a separate ground wire at the housing causes the light to come on, the ground wire is bad. You can also check for continuity between the light blue wire at the brake light switch and the lamp housing and the same for the ground wire.
Also check the ground wires at the lamp and at the ground connection for corrosion or loose connections. For coupes, the ground wires will be at the right hand side of the cargo compartment, rear of wheelhouse. The ground wire post should be below the right hand shoulder belt attaching point.
The brake light switch sits above the brake pedal. The 3rd brake light wire is light blue and is in cavity C of the connector. Depressing the brake sends voltage to the 3rd brake light. Check for 12v at the wire going into the lamp housing.
If a separate ground wire at the housing causes the light to come on, the ground wire is bad. You can also check for continuity between the light blue wire at the brake light switch and the lamp housing and the same for the ground wire.
Also check the ground wires at the lamp and at the ground connection for corrosion or loose connections. For coupes, the ground wires will be at the right hand side of the cargo compartment, rear of wheelhouse. The ground wire post should be below the right hand shoulder belt attaching point.
Racer
Joined: May 2004
Posts: 295
Likes: 3
From: Newton NJ
Another thought is to take the light physically off the car and check the wires. Some body shops like to cut the wires for the third light to remove it for painting. They will then forget to splice them back together when they put the light back on the car. Ask me how I know
Last edited by cmontel727; Apr 8, 2008 at 07:59 PM. Reason: I suck at spelling
Race Director
Joined: Sep 2000
Posts: 12,182
Likes: 1
From: Partying with the Cowboys cheerleaders in Mt. Olive, New Jersey
Another thought is to take the light physically off the car and check the wires. Some body shops like to cut the wires for the third light to remove it for painting. They will then forget to splice them back together when they put the light back on the car. Ask me how I know
Racer
Joined: Oct 2002
Posts: 416
Likes: 2
From: Westfield MA
Exactly what happened on my '87. I had about 11.5 volts at the light socket but the bulbs wouldn't light at all. It was the brake light switch at the pedal.
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