Brake lights won't shut off

[ragtop]

Hello BCF,
Long time reader, first time call for help! My 69 TR6 is running fine but I just discovered my rear lights (not the blinkers or reverse lights) stay brightly lit when the car is running. I'm underwater when it comes to electrical problems but I guess there is a grounding issue somewhere. If so, where should I start looking? I do need to start figuring these circuits out and this should be a good beginning. I will appreciate any and all advice you have.

 

[DNK]

First place is the switch under the brake.
Make sure it is not stuck.
Also with the car running ,wiggle the wires at the back light area

And welcome to the party Pal

 

[Andrew Mace]

I would think it's almost certainly the switch. If you're lucky, it might just need some adjustment, or it might be jammed or shorted? Many of those switches are only plastic (either Lucas or Delco brands that I've seen over the years), and it's somewhat remarkable that they last 40 years or more!

 

[TR3driver]

Could also be the brake pedal not returning as far as it should, for whatever reason.
The problem is not likely to be at the rear lights, since there is normally no power back there unless the tail lights, etc are supposed to be on.

 

[DNK]

Good point Randall, no reason to have juice there so must be upstream

 

[John_Mc]

I was not electrically inclined when I started this hobby, but luckily the electrics in these cars is so straightforward that even one as I can quickly figure it out. A big help is a proper wiring diagram which can be found at Advance Auto-wire. Click on "Stock Schematics" on the left hand side. Then scroll to the bottom and find the link to the PDF file for your model. Voila! A nice thing to do is take the diagram on a thumb drive to Kinkos and have them print you out a LARGE copy and have them laminate it. Hang it up in your garage next to the Farah Fawcett poster and your interior decorating is complete! FYI, my brake switch went bad a few years ago and I replaced it at the local auto parts store with a switch for a Ford Escort. Won't win me any concours awards, but it works great.

 

[DrEntropy]

Andy and Randall likely nailed it. Only way power gets to the rear bulbs is if the switch is activated or defective... or a PO did some "creative" wiring changes.

 

[ragtop]

Thank you all for the illuminating replies. It turned out to be an easy fix once I was able to slide under the dash. The plunger was not making contact and I was able to adjust the nuts to do so. I did note that the lights before the adjustment were very bright, more so than after the repair. Now they appear to be of a normal light level. Why would that happen?
Thanks again for all the help - Chris

 

[Andrew Mace]

Chris, you might now be seeing a bit of a grounding issue. What happens when the taillamps are on and the brake pedal is pushed? If the grounds are poor, there's a good chance you'll see the bulb go dim rather than get brighter. (Nothing like multiple issues, eh?)