Can someone explain brake light power flow to me?

[Tomsriv]

Step on brake, power goes from Orange in the Stop Lamp Switch to the White. The White goes to the directional signal connector and then????

Should it send batt voltage to both the green and yellow wires? Currently it does not and my brake lights do not work.

My turn signals work, my running lights work, (power to brown wire in stop tail)
The directional signal connector was replaced just a few thousand miles ago.

What could be causing the problem?

[jocko]

if your turn signals are workin, to me that means your turn signal sw and wiring/power to the tail lts for that function is working correctly. That leaves the brown power wire, and you mentioned you had power to that.

Only 2 things I can think of:
- bad ground (try hooking a temp wire/alligator clip to ground the housing to something so you know you have a solid ground).
- possibly incorrect bulb type (does it have 2 filaments in it?)

Probably neither of those - I HATE electrical problems, but that'd be my next 2 checks. After that, I'm stumped. Good luck, interested in hearing what it turns out to be.

[jocko]

One clarification - the brown wire is for the running lights, as you mention. The yellow is for directionals and stop on the left - green is for directionals and stop on the right. So, on top of what I mentioned above, I'd check to see that you have power to the yellow and/or green WHEN the brake pedal is pushed. If not, then all I can think of is what I mentioned above. Sorry, probably not much help.

Tomsriv - re-read, and to answer your question, Yes, I do believe that power should be going to your GREEN and YELLOW tail lt wires when you have stepped on the brake pedal and the turn signals are off. Sorry, I should have read more carefully. If you're not getting power to those when depressing the brake pedal, then the issue is probably not either of the things I mentioned. I'd guess it would be the turn signal switch - but you said you recently replaced it, so I'm kinda stumped right along with you.

[Tomsriv]

Thanks for the reply Jocko, its good to know I'm not going crazy. I guess I'll try jiggling the turn signal lever and see if that makes any difference.

[66BowTieBoy]

Tom,

Yes, the Green & Yellow wires send 12 volts to the lights when you depress the brake pedal. If you have power coming from the stoplight switch (white wire), and your turn-signals function, the power is getting lost between the brakelight switch and signal switch output. Since you recently replaced the signal switch my guess would be a loose connection after the brake switch or in the signal switch.

Grab your test-light and happy hunting.
Danny

[PAPA KENT]

I agree with 66bowtieboy

[blackmopar]

Im having similar issues - reported in the electrical subforum under this thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=440858

driver side stoplight works, psgr does not - all else is fully functional

Ive deduced it to be a TurnSignal Switch problem and have one on order from Chevy Duty - should have it on Thursday and Ill report if it is the fix.

I determined this by tracing white brake pedal lead up to switch in the column - 12v hot when pedal activated.

Yellow also gets hot - Green does not

couldnt get any response jiggling the turn sig lever

[Tomsriv]

I figured it out after putting this off for a while. I have a newer steering column so your may be a little different. This connector was not tight at the top where the wires from the turn signal come it. Can you tell by looking at it? If you look very closely you can see the top is not as tight as the bottom. So when I squeezed it together the brake lights started working again. Keep in mind the turn signals worked all this time. I wrapped it in zip ties so it will stay tight. Its amazing how much grief loose connections have caused me on this truck. The turn signals on the hood are a whole 'nother story.