Brake lights switch replacement

[russvanp]

Hi. I’m a pretty inexperienced mechanic, and having troubles with my brake lights. Turn signals work as well as clearance lights. But no brake lights. It’s been intermittent but now it’s always. I think I found the switch under the dash near the top of the brake pedal arm. There is power to one connector but not the other. Can anyone give me advice on how to access the switch to replace it?

Thank you
Russ

[russvanp]

Sorry. I have a 62 shortbed 1/2 ton GMC pickup

[lizziemeister'sV6]

Brake switch is in series with the power (+) wire - so only 1 terminal is powered all the time and the other terminal is powered only when the push button is depressed by the brake pedal. You should purchase yourself a manual for your truck - very helpful for yourself.

[James]

I went and looked at my 64, I don't know if it the same (see attachment). I would unplug the two connectors. Then with a wrench, reach through the large hole and loosen the pal nut. Then unscrew the switch from it mount (you might want to count the turns so you can install the switch back in).

Hope this help.

[Jim A]

The switch is easy to see but a pain to work on.
Keep in mind that there is a ridiculously complicated turn signal switch on the steering column that allows the same light filament to be used for brake and turn signals.
It is also hard to work on and I had to give up on my '60 3/4 about forty years ago and go to a separate three way switch and external turn signal.

[AZKen]

Hello Russ, the first task with an electrical problem is to troubleshoot and discover what part or what issue is at fault. Some folks assume and start replacing parts. That can work also. Click on AZKen, find profile, find my email address and send an email to me if you wish to test a little.

As far as your question, it's down under. It is actuated by the pedal arm. You will see two wires. If you are flexible and can bend your body, you can get to it and remove as James describes. Your trouble can be a lot of things other than the switch. A few test my give the answer.

This is what it looks like click

[James]

Originally Posted by Jim A

The switch is easy to see but a pain to work on.
Keep in mind that there is a ridiculously complicated turn signal switch on the steering column that allows the same light filament to be used for brake and turn signals.
It is also hard to work on and I had to give up on my '60 3/4 about forty years ago and go to a separate three way switch and external turn signal.

He right. Once you step on the brake, power is routed to the turn signal switch. The brake light is also the turn signal light (same bulb).

So the question is, are you getting power out of the brake switch when you push on the pedal? If not, then it the brake light switch or a sticking brake light switch. Try spraying WD40 on the plunger if you can access it to free it up and see if it fix it. If not, then try a piece of wire between the two connector from the brake light switch. It will route power to the turn signal switch. Also make sure that power going through the steering column connector. See if the brake light come on. If it did, replace the brake light switch.

If you are getting power out of the brake light switch, then the turn signal switch might be your problem.

On my truck I had a bad connection at the turn signal switch, left side was intermittent. Found to be a loose rivet where the wire lug is attached to the switch. Set the rivet a little tighter, problem gone.