Strange brake light problem.....

[vincewarde]

I have a 1993 EB and I am having a very strange brake light problem.

1) Intermittently, either the left or right brake light fails to work. When this happens at one side always works. They never fail completely.

2) Whatever side fails, that side also is not lit up on the factory trailer brake circuit.

3) I have had to pull the fuse on the cruise control because it blows brake light fuses when it is used.

I believe that the Gen I Explorers have a four circuit rear light system (Running lights, brake lights, turn signals. and backup lights), while the trailer system uses the same lights for both brake and turn signals. This requires an adapter to mediate between the two systems. I'm thinking that, given the symptoms, this is where the problem lies. Does anyone know where this unit is located? Is it still available? Thanks!

 

[arco777]

90% sure it is your multifunction switch, which gets worn and sloppy. Try backing up to a garage door or other somewhat reflective surface so you can see the glow of your brake lights, or have someone watch. Step on the brakes while you wiggle your turn signal up and down (right/left) both directions. I bet you will see the lights on each side go out. The switch gets old and needs to be replaced. I used a junkyard switch, it is very easy to change and takes only a few minutes.

 

[vincewarde]

90% sure it is your multifunction switch, which gets worn and sloppy. Try backing up to a garage door or other somewhat reflective surface so you can see the glow of your brake lights, or have someone watch. Step on the brakes while you wiggle your turn signal up and down (right/left) both directions. I bet you will see the lights on each side go out. The switch gets old and needs to be replaced. I used a junkyard switch, it is very easy to change and takes only a few minutes.

You called it! That is exactly what the problem was. I ordered a nice new switch off of eBay for less than $50.00 and:

No more weird brake/turn signal problems.

My Cruise Control no longer blows fuses!

While I was at it I replaced a buggy light switch and all my dash lights - most of which were burned out (with help from my small handed wife). Wow - a couple of hours work cured a lot of problems.

Thanks!

 

[Tony H]

Nice job...
Nice fast diagnosis by ARCO777
This is a typical Multi function switch issue.