No brake lights

[grayman67]

Hello GBody forum,

I look forward to sharing in the potential knowledge wealth and experiences within this forum. Now to the issue; I have a 1979 chev monte carlo. The problem is I have a functional exterior lights front and rear with the exception of my brake lights. I have replaced the brake light switch, checked the fuses all to no evail. Any suggestions would be appreciated.

Cheers,

Callistus

 

[79 GP 4 speed]

Do your turn signals work? Have you checked to make sure you have power to the bulbs?

 

[grayman67]

Do your turn signals work? Have you checked to make sure you have power to the bulbs?

Yes,both front and rear are functioning

 

[grayman67]

Yes,both front and rear are functioning

The bulbs in the rear are working, the unusual thing is the brake bulbs are 1157,the parking lights work in the bulbs but no brakes light filaments work.

 

[Built6spdMCSS]

Turn signals are the same filament the brake lights should be if I'm not mistaken. Check the wiring at the brake light switch connector and then from that connector to the rear.

 

[popeye1978]

If I remember correctly, signal is:
12V at battery --> Brake Switch --> Turn Signal Switch (which contains the mechanical switches that "decide" between Solid-Brake or Flashing-Turn-Signal) --> bulb & ground

As Brake Switch has been replaced, sounds like a problem at the Turn Signal Switch

 

[grayman67]

Turn signals are the same filament the brake lights should be if I'm not mistaken. Check the wiring at the brake light switch connector and then from that connector to the rear.

Hi Built6spd, The wiring seems to be in good order, no presence of damage. The brake light bulbs rear are 1157 two separate filaments. 1 is dedicated to the park lights (which work) and the second filament for the brake circuit( not working). All of the other lights are functioning.

 

[grayman67]

If I remember correctly, signal is:
12V at battery --> Brake Switch --> Turn Signal Switch (which contains the mechanical switches that "decide" between Solid-Brake or Flashing-Turn-Signal) --> bulb & ground

As Brake Switch has been replaced, sounds like a problem at the Turn Signal Switch

Hi Popeye1978,

Thanks for the post, if the turn signal switch were faulty, would the signal lights continue to function with the switch?

 

[Built6spdMCSS]

Hi Built6spd, The wiring seems to be in good order, no presence of damage. The brake light bulbs rear are 1157 two separate filaments. 1 is dedicated to the park lights (which work) and the second filament for the brake circuit( not working). All of the other lights are functioning.

I am familiar with the bulb, what I'm getting at his check at the connector for 12V constant power, and then check the wiring going back to that filament on the connector at tail lights and make sure it's good.

 

[popeye1978]

Hi Popeye1978,

Thanks for the post, if the turn signal switch were faulty, would the signal lights continue to function with the switch?

Depends on the fault ... maybe there is a problem with the Brake wire -- from the Brake Switch -- in the connector between the Turn Signal Switch [Harness] and the Body Harness. Maybe the "Brake Light" contacts in the Turn Signal Switch itself are worn-out so they are no longer conducting electricity. As the rear turn signals are working we know the wiring from the Turn Signal Switch to the bulbs is intact.

Built6spdMCSS has a good point about checking for 12V at the Brake Switch connector -- that circuit is always hot (so even if the ignition is OFF you still have brake lights to serve as a warning to other cars) so when you disconnect the Brake Switch from the harness, a volt-meter should measure 12V when you put one lead against a body ground and whichever terminal on the Body Harness leads back to the fuse box.