Brake light/turn signal puzzle

[kdgauger]

Have problems with my brake light/turn signal on a 1991 Mazda Navajo. I have replaced the bulbs so that isn't a problem. There are 2 filaments in the bulb. One is the tail light and the other is brake light/turn signal. If I just push the brakes, nothing lights up. If I turn on the turn signal, it works but if I also push the brakes, the brake overrides the turn signal and the bulb stays lit. So the brake switch is working, the turn signal is working and the bulb is good.

 

[Anime]

In normal operation, the brake doesn't override the turn signal - the turn signal keeps blinking even when the brake lights are "on", even though it's just one side.

It might still be the brake switch gone bad, a relay that's stuck, or a wiring issue. Also be sure the bulbs were replaced with 3157 bulbs and not something that just looks similar but is another bulb number with different specs.

 

[kdgauger]

I did use the 3157 bulbs. I am going to test the multifunction switch next. Thanks

 

[kdgauger]

Still unresolved

Looked at my brake light/turn signal problem again. The 3rd stop light over the tail lid is the only brake light that is working. The turn signals work (and click) UNTIL I put on the brakes and then NOTHING. Light quits blinking and turn signal quits clicking on the inside. Any suggestions?

 

[awood]

Do you have a plug for a trailer? If someone hacked in the wiring for a trailer plug, I would remove it and repair any damaged wiring.

Also, what happens if you just turn on your hazards (not turn signal) and then applying the brake? If all seems okay there, try swapping the hazard and turn signal flashers.

You are correct in assuming the brake switch is good if the 3rd brake light is working. The switch feeds power directly to that light.

Double check the lamp sockets on each corner of the Explorer. Sometimes the sockets can deform from overheating and do weird things.

That said, a likely culprit is the multifunction switch.

 

[kdgauger]

After removing & testing the multi-function switch, I decided the switch was the problem. Replaced the switch and my brake lights are WORKING! Thanks awood.

 

[arco777]

Glad you got it fixed. Most problems with taillights are caused by the multifunction switch. Fortunately it is easy to replace.