I have a 1989 GMC Sierra c2500. When I press on the brake pedal, my brake lights do not come on. At first I thought the bulbs were burnt out, but when I took the bulb out and tested it with electricity it...
Buy a cheap test light to run simple tests to see where power is being lost. Start at the brake light fuse. Clip the ground lead of tester to a metal bracket or bolt under the dash. Then use the tester's probe to touch the little indents on top of the fuse. There are two indents on each side of tops of fuses-these are test ports to check if a fuse has blown. The brake light fuse will be "hot at all times", so touching the metal strip inside the indent should light up the test light. If not, check if your ground clip is good: turn the key to on. Now every fuse in the dash panel should be powered. Every fuse should light up the tester. If both indents on a fuse light up the test light, that means it is a good fuse. If only one side lights up the tester, that is a blown fuse.
Now back to the brake light fuse, key off. Does it show power? If not, maybe a fuse link off the battery that distributes power to the fuse panel has burned out. If fuse shows power at both ends, move tester to the brake light switch and check for power at the switch-this wire to brake switch is again "hot at all times". Should have power in, and when brake pedal is depressed switch should also have power out. From the brake switch, the brake signal wire goes up into the turn signal switch, and is then routed out to the brake lights. With pedal depressed, you can check for power in and power out at the turn signal connector. Don't pull the connector apart, but back probe the connector with the test light probe. You know the color of the brake light wire from brake switch to the turn connector, so easy to check for power in. Power out should be on two wires, one for each side of the rear lights. If the turn signal switch has power in but no power out, with brake pedal depressed, probably a defective turn switch.
Post back with results, or when you find the problem.
Aug 12, 2013 |
Cars & Trucks