Brake lights, tail lights, turn signals, HELP

[white1983gt]

O.K. I've seen several posts similiar to this, but none have answered my question. I've noticed that sometimes my turn signals blink really fast, when this happens the brake lights work, but they are REALLY dim, and the brake lights do not work at all if the headlights are on. All my bulbs are new, and I've tried a new circuit board, neither made a difference. The problem will last for a day or two, then it will go away for about a week. Finally with a test light hooked to the harness under the truck when I'm having the problem, I have good ground, and I can get the "blink" from the blinker, however I don't have a second set of hands (or feet rather) to press the brakes and test them. Please help this is driving me nuts......I'm ready to sell the truck, and I just got it.

1993 GMC Sierra SLE Ex-cab step side 2-wd

[Jeremy-WI]

Check the battery connection for corrosion and check the battery grounds. It sounds like the path to ground is restricted("the brake lights do not work at all if the headlights are on")

[white1983gt]

Well, I checked the battery connection, and it was spotless. By the way right now, it has been three days since the taillights have worked, normally they are "better" by now. They did work once when I tested them yesterday, but today they havent worked at all.
Is there perhaps a chassis ground i can check? This is really driving me crazy.......

In the meantime I was thinking maybe the wires had moisture in them, or at least the connection, so I dried the connection with a hair dryer, and it still didn't work, so I checked them for continuity, and they tested ok. I also removed all of the paste from the connection while I was in there. Any other ideas?

[white1983gt]

COME ON people some one has to have a heads up on this. playing with the truck tonight, the park lights came on for a minute or so. When the lights are working, I get the battery voltage at the bulb sockets, when they aren't of course....zero. When the lights aren't working, I also noticed that the cargo light ground seems to go dead. Finally when you cut on the right blinker (when the lights aren't working of course) it seems to take a few seconds to "warm up" before it begins flashing, and with the hazzard lights on, when I cut on the headlights the flashers become brighter PLEASE HELP, SOMEONE ANYONE!!!!

[white1983gt]

FYI it was a frayed wire to the pass. tail light.