Brake light issue, 1981
Thread Starter
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Joined: Sep 2001
Posts: 93
Likes: 3
From: Houston TX
Brake light issue, 1981
I am perplexed by a new brakelight issue on daughter's '81, I hope you guys/gals can offer suggestions:
Facts:
- Brakelights do not work when brake pushed.
- Lghts work properly in other functions: parking, turn signals, emergency flashers (flashers means shared fuse is good, too).
- Wires in plug going to the switch have 12v.
- Switch contacts are not closing when plunger moved (so it is the switch, right? Well, here is where it gets interesting
- After plugging in new switch, which I verified does open/close contacts when the plunger is pushed, lights still don't work.
- Shorting wires across plug does not activate lights.
Questions:
1. What am I missing? Maybe a short between plug and "control box"? I have 12v going somewhere!
2. Where is the "box" that covers all the taillight controls (#144 from diagram, I believe- diagram is downstairs?)
It is awful tight under that dash...
Thanks for any help.
Facts:
- Brakelights do not work when brake pushed.
- Lghts work properly in other functions: parking, turn signals, emergency flashers (flashers means shared fuse is good, too).
- Wires in plug going to the switch have 12v.
- Switch contacts are not closing when plunger moved (so it is the switch, right? Well, here is where it gets interesting
- After plugging in new switch, which I verified does open/close contacts when the plunger is pushed, lights still don't work.
- Shorting wires across plug does not activate lights.
Questions:
1. What am I missing? Maybe a short between plug and "control box"? I have 12v going somewhere!
2. Where is the "box" that covers all the taillight controls (#144 from diagram, I believe- diagram is downstairs?)
It is awful tight under that dash...
Thanks for any help.
Thread Starter
Advanced
Joined: Sep 2001
Posts: 93
Likes: 3
From: Houston TX
OK, update: the switch was good, obviously the negative side has a short, or the module that it goes into doesn't work. So, where is the flasher/brake/hazard switch assembly? I trace the wire out of the brake pedal switch & lose it. The shop manual doesn't provide much help.
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
Not very good news, but this is what you need. The brake circuit goes from the brake switch through the turn signal switch assembly. Could be just the wire connection on the harmonica connector under the steering column.
Thread Starter
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Joined: Sep 2001
Posts: 93
Likes: 3
From: Houston TX
Thank you! Your color pic is SOOOOO much better than the black & white one in my shop manual- I can actually SEE things inside the switch, instead of a grey/black blob! 
Two dumb questions: 1) so the turn signal switch assembly you reference is where, exactly- in the turn signal/cruise lever body that I move when turning the signals on/off? Obviously I haven't torn into the column before...
2) Where specifically is the harmonica connector? The white wire from the switch seemed to disappear around/behind the top of the fusebox.
Thanks again for the info- this really helps.
Two dumb questions: 1) so the turn signal switch assembly you reference is where, exactly- in the turn signal/cruise lever body that I move when turning the signals on/off? Obviously I haven't torn into the column before...
2) Where specifically is the harmonica connector? The white wire from the switch seemed to disappear around/behind the top of the fusebox.
Thanks again for the info- this really helps.
Le Mans Master
Joined: Aug 2006
Posts: 7,431
Likes: 1,561
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The turn signal switch is in the column.
The harmonica connection is near the bottom of the column.
Power goes from the brake pedal switch to the harmonica connection and up the column to the turn signal switch. See if you have power there.
Power comes down the HC on the N & M, See if you have power there.
The harmonica connection is near the bottom of the column.
Power goes from the brake pedal switch to the harmonica connection and up the column to the turn signal switch. See if you have power there.
Power comes down the HC on the N & M, See if you have power there.
Intermediate
Joined: Apr 2012
Posts: 29
Likes: 0
I had similar symptoms to you on my 75 and there was a broken wire at the harmonica connector. I could get the lights to work temporarily by moving the wires around. I Hope it's something similar and not the turn signal switch - I read up on that when troubleshooting mine and it looks like a PITA!
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
I would suspect either the brake light switch and/or the wire labeled as "17" in that schematic. It could be the wire or the connections at either end. Use an ohmmeter and check along that line for electrical integrity (continuity).
Thread Starter
Advanced
Joined: Sep 2001
Posts: 93
Likes: 3
From: Houston TX
Thanks again for the help, guys. The problem turned out to be a bad connection in the harmonica connector on the steering column... or at least they haven't failed again since I found & fixed that!
J
J
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