I have a 1998 Mustang Convertible gt and the passenger brake light works intermittently I have cked every wire.The only time my brake light works if I put the right directional on first but then when the next time I step on the brake it doesn't work again, then it will work sometimes on it own. I have to remind myself everytime I step on the brake to but the directional on quick......grrrrr. This is driving my absolutely crazy! I had a few ppl look at it and they are baffled as well. parking lights and directional work. I also cleaned out harness. Help it's driving me crazy and I don't want to get pulled over again.

 

Have you checked the bulb? Sometimes the filament will go funny before it fails altogether.

 

yes, I have also change all the bulbs.

 

Have you checked all of the grounds? You might try adding a ground wire to the the light bulb socket and run it to a known good ground.( you can clip or hold a wire to the socket ground) You should be able to put the plus side of a voltmeter on the ground part of the socket and the minus to a good ground, if you see more that about .5 V you have a poor ground.

 

I finally found out what it was.... it was the multifunctional directional switch. It was an easy fix. I hope this can help someone who has the same problem.

 

Glad to hear that. Was it hard to replace?

 

Not at all just took the column off and the switch has two screws and pull the two plugs out and plug in the new one screw back in pit column back on oh and I forgot about the under dash plate needs to come off to but all easy peasy.😀

 

Where is the switch located?

 

It's in the steering column

 

Multi-function switch is the turn signal lever. Since it also has controls for the wiper, hence the "multi-function" in the name.