# 1966 GTO Brake Light/Turn Signal Problem



## Indecision (Oct 24, 2010)

The turn signals and brake lights went out at the same time and I haven't been able to find the culprit. If I put the parking lights on, the front parking light/turn signals illuminate, and the tail lights come one. With the headlights on, parking light/turn signals go back out up front and the tail lights stay on as they should. But the brake lights don't illuminate, and the the parking lights/turn signals stay dark up front. 

A fuse blew when they initially went out, checked everything I could find, found no issues. Replaced the fuse, checked the brake lights, they worked and I thought the problem was fixed. Clearly I was wrong, fuse is currently still good. 

The turn signal indicator MAY have gone out prior to the actual turn signal failure. When it stopped working, I want to say I could still see the reflection of the front turn signals in the car in front of me. But that could've been my imagination or something, and if that was the case it was within a day or two of the turn signals/brake lights failing. 

I've replaced the flasher and tried to replace all the bulbs I could. I'm replacing all of the sockets for the tail lights this weekend, 3 of them are in shoddy condition so they don't have bulbs in them. They were in bad condition before, bulbs had to be taken out with pliers type of thing, but the tail lights and signals worked when they were bad before so I don't believe they are the problem. I could be wrong, of course. 

I found a wiring schematic, but at the least the one I found didn't have a common power or ground wire for the turn signals/brake lights that I could see, which is the only thing that makes sense to me. 

I'm sure there are millions of things it could be, but I'm just hoping someone may have SOME clue and could point me in the right direction, there's a rat's nest from hell under the dash I'm hoping to avoid. I've got a multimeter and test light so I can test anything anyone can point me towards, I'm just not sure where to start.


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## pjw1967 (Mar 10, 2014)

Check the bulb housing for the interior light. If the '66 is like my '67, it uses spring clips to hold a small torpedo bulb. I somehow managed to push the spring clip thru the housing so that it was grounding on the underside of the roof. I think that bulb is on the same fuse as the brake lights.


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## geeteeohguy (Feb 2, 2008)

Be advised that on a '66 and '67 GTO, the parking lights are _supposed to be out with the headlights on._ The only thing that is illuminated with the switch pulled all the way out is the headlamps and tail lamps, period. Check the horseshoe connector under the steering column and the brake light switch. Also run a jumper ground wire to the rear tail light assembly or bulb.....the pigtail bulb holders go bad and lose their ground. Good luck.


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## Indecision (Oct 24, 2010)

I'm aware that just the tail lights and headlights are supposed to be on with the headlights on. I was attempting to explain, apparently poorly, that the parking lights were working as they should, but the turn signals were still not functioning correctly though they worked correctly in a separate capacity. 

I plan to check the brake light switch as a matter of being thorough, but at least looking at the wiring diagram I have, it appears the brake light switch failing would not cause the front and rear turn signals to stop functioning as well.


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## geeteeohguy (Feb 2, 2008)

That clears it up a bit! Again, check the horseshoe connector and check grounds and voltages at the lights. The fact you have working front turn signal lights when in park position means the lamps/bulbs up front are ok. You could very well have a bad turn signal switch, a wire issue at the horseshoe connector, a bad flasher, and/or bad grounds. Probably not the brake light switch, but it's very easy to check.


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