So two days I fixed the back left turn tail light signal/brake light they finally lit up. Yesterday the left one just doesn't turn on now but it does light up with the parking light just not the turn signal/brake and now my right one flashes real slow when I turn on my parking lights/beams I don't know why. I replaced the socket the bulb and fuse and the crappy job the previous owner did back there. So any suggestion would be greatly appreciated. Also it's a 81 c10
First, determine if the problem is on the hot side or the ground side of the bulb.
Pull the bulb and turn on the parking lights. Go back to the socket - and using your meter or test light - check each of the contact "buttons" at the bottom of the socket for voltage. Only one should be hot. That one supplies power to the low wattage filament in the dual filament lamp (i.e. the parking light filament). That is
not the one you are concerned with.
The other one is the contact for the higher wattage filament (i.e. the T/S & B/L filament) - and that
is the one you will want to check. Have an assistant step on the brakes (or lay a cinder block on the pedal if you have no helper) and go back to the socket. Look over at the RH assembly and see if that brake light is illuminated. If it is on, that means that your helper is doing a real good job - or your brick is holding the pedal down. Now, check for 12 VDC at the non-parking light button in the problem socket.
If that button is
not hot, you have a open in the yellow wire somewhere between the splice plug and the socket. The yellow lead is the common power supply for both the brake and directional lights. Both circuits use the same high wattage filament. You know power is available at least up to the splice because the RH side brake light is lit.
If the button is hot, there is an issue with grounding. I am not familiar with the rear lighting harness is for the 1981 models. Specifically, I don't know how the rear lamps are grounded - each side separately and locally or both sides spliced together and sharing a common ground point. But regardless check the black wire coming from the back of the socket and make sure it is making good contact with the frame at it's termination.
