wiring Gods help

[SS317]

I have been troubleshooting wiring for a while now. Here's my question, the brake lights come through the switch on the petal and then runs up to the blinker assembly. What would it hurt if I rerouted it direct from the petal switch to the back lights? The wiring diagrahms I've been looking at don't show any reason that that signal needs to be up there.

[losthope]

you can bypass the turn signal switch to have just brake lights but wont have anyturn signals if thats what your asking it wont hurt anything, just make sure when you have your headlight switch pulled out that you still have running lights also..itll be just like a 50's car that didnt come with turn signals, thats the way i have my truck wired at the moment because the guts of the turn signal switch are shot and i need to replace it..

[Indian113]

Me TOOOOO!

[SS317]

I was thinking of just splicing into the side of the switch that puts out 12vdc when you press the pedal. Not cutting out the constant 12vdc that is there for turn signal operation.

[Alan's Classic]

Moved and a bump

[fixit-p]

If you want combination stop/turn lights the brake light has to run through the turn signal switch otherwise you would need separate circuits for the turn signals.

[tincan1966]

A good question- what is the problem you are trying to fix? Yes you can eliminate the brake light circuit running thru the TS switch, but you will no longer have turn signals.

All you'd have to do is splice the yellow and green wires from the T/S switch to the white wire coming off of the brake light switch. Again, you'll have no turn signals at all, front or rear.

[SS317]

I'm not understanding why I won't have turn signals anymore? There is a constant 12vdc for the turn signals that is unrelated to the brake 12vdc, unless I'm not seeing something.
AND I was going to splice the wire not cut it. I'm just thinking of giving it an alternate path to the back lights, keeping the wire intact to the turn signal.
Thoughts?

[tincan1966]

If you just cut and splice the harness, your rear lights will not operate properly ie: with right T/S on the left will not be constant, as a brake light. The circuit is designed to operate the way it is wired.

There should only be switched (key on) power to the T/S switch and constant to the brake light switch.
There is no need for an "alternate path" to the lights,with proper grounding and a correctly operating T/S switch iit all works great.

These trucks have a pretty simple wiring systems that works really well,the main fault is poor grounding to the tail lights and hood mounted turn signals in front.

Still curious if there is a problem yu are trying to solve?

[SS317]

Problem is the brake lights aren't coming on at all. I can trace the voltage up to the connector that goes to the turn signal assembly. I replaced it last year (turn signal assembly) but everything I've done points toward needing a new assembly.

[fixit-p]

Originally Posted by SS317

I'm not understanding why I won't have turn signals anymore? There is a constant 12vdc for the turn signals that is unrelated to the brake 12vdc, unless I'm not seeing something.
AND I was going to splice the wire not cut it. I'm just thinking of giving it an alternate path to the back lights, keeping the wire intact to the turn signal.
Thoughts?

The left and right brake lights are two separate circuits, they have to be for the combination stop/turn circuit to work properly. If you bypass the turn signal switch with the brake light circuit you would have to connect it to both the left and right bulbs this creates a short circuit and regardless of which turn signal you have both lights will flash. With the brakes applied it would override the turn signal and neither will flash. The front tuns signals will not be affected.

[SS317]

Originally Posted by fixit-p

The left and right brake lights are two separate circuits, they have to be for the combination stop/turn circuit to work properly. If you bypass the turn signal switch with the brake light circuit you would have to connect it to both the left and right bulbs this creates a short circuit and regardless of which turn signal you have both lights will flash. With the brakes applied it would override the turn signal and neither will flash. The front tuns signals will not be affected.

Now that makes sense but what is the 12 volts that is only there when the brake is applied doing up at the turn signal switch? I found the 12 volt constant up there for the turn signal, and I don't want to touch that one. I want to splice into the other side of the switch on the brake pedal, that only has 12 on it when the pedal is pressed. I can follow that 12 up to the turn signal connector but don't know where it goes from there.

I was an avionics tech on airplanes, so this wiring doesn't scare me any, I just wish I had better schmatics of the system.

[tincan1966]

The 12V going to the T/S switch is how the brake lights operate. For the signals to work properly and not both flash at the same time, there is canceling contacts within the switch.
It would be far quicker and simpler to replace the defective switch,and have everything work as it should.IMO
There should not be any 12V constant(key off) going to the turn signal switch unles the brake pedal is depressed,then that is normally a white wire.
There are some good diagrams on this site,but I do not have a link to them.

[fixit-p]

The 12 volts from the brake switch goes through the turn signal switch because depending what position the turn signal switch affects brake power distribution to the rear stop/turn lights. For example when the switch is set to left turn and you apply the brakes the turn signal switch diverts brake switch power to the Right brake light but not the left otherwise the left bulb wouldn't flash because the constant power from the brake switch would override intermittent power from the turn signal flasher. It is opposite for the right turn and when the turn signal switch is not active brake switch power is directed to both brake lights. Double check that the hazard button is not pulled out, with the hazard switch active it could block the brake switch signal to both brake lights.

[fixit-p]

tincan1966 beat me to the post but we are basically saying the same thing. Double check the hazard switch.

[SS317]

Hm, there is no hazard switch on my 66. I ordered a new harness from the firewall back to the tail lights. The old wiring is brittle and there could be some shorts in there somewhere. I'll start with that and see what happens. Thanks for all of the help guys, I appreciate it.