99 Chevy Tahoe. 4x4 4 door. The brake lights have stopped working except for the light bar above the rear door. I have tested the brake lead under the dash and have found it to be in working order. I have followed it to the molex in the firewall. I have tested all other wires that lead to the rear in a few spots under the vehicle. Each spot shows the same results of Running lights 13 volts, turn signals working, reverse working but no power for brake lights. Can someone please help me here, I usually figure these things out pretty quickly but this one is really giving me problems.
Thanks
Shawn
All fuses have been checked and double checked. Again, the LED light bar above the rear window/tailgate comes on but the two lights on either side do not. So I can conclude that the switch is still good and has power. I have removed every fuse in the tahoe and made sure there wasnt something blown. I have also found the brake lead under the dash and Im getting 13 volts at that lead. Its somewhere between the firewall and the rear of the tahoe.
Bulbs have been checked and even replaced. I have thought about running new wires if need be. I even tapped the brake lead under the dash and pluggen it into the brake lights in the back and they worked perfectly when I did this. I know its something in the harness, but what?
Twice this year I have had brake light problems and turnsignal problems. 1998 2 door tahoe with barn doors. I had to remove the bulbs clean the connection area out and keep rechecking. they eventuly start working. I know they make replacement bulb housing for those. I think I will replace mine next year
Keep in mind, while your trouble shooting, that it is apparently in a part of the circuit that is common to both sides but not to the light above the doors or hatch or whatever.
You may have shorted circuit boards. A common problem in that model year range. Do your turn signals work? I have a '98 pickup and have replace both taillight boards so far ($75 ea.) usually one side or the other, not both at the same time, look for discoloration around the bulb socket.
I was told the brake lamp tends to overheat them, excess load of trailer lights may contribute to the problem.
Check the white wire from the brake light switch to the turn signal switch plug. Repair if necessary. This wire feeds power from the brake light switch through the turn signal switch. The wire may have broken off the switch or broke inside the colum. You may be able to repair the switch if you see a broken wire.
If your turn signals are working and no brake lights it usually means the turn signal switch is bad. Your brake light switch sends power through the turn signal switch. Your brake lights and turn signals share the same element in the bulb. So if the turn signals are working you know that the wires and bulbs are good.
The brake light switch is working that why you get the 3rd brake light only, it is fed directly from the switch and does not go through the turn signal switch.
It's not uncommon to loose only one function of the turn signal switch, requiring you to replace the entire switch.
Yep, what he said ^^^^^^^^^^^.Pretty standard for all the vehicles where the turn signals and brakes share a bulb filament.
Thanks guys! Ill get a turn signal switch tomorrow and see what I can do.
if your high mount stoplamp is working than its definately a fuse, there's a stoplamp fuse under the hood in the fusebox on the driver's side fender. your stoplamp fuse is blown, the high mount has its own fused circuit independent of the rear stoplamps
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