Brake light always on

[Peter Westling]

Hi all.
I have searched the forum and did not find any clues...

I have a 93 XLT and the the brake lights is constantly on.
I checked the "stop lamp switch" at the pedal. I thought it might be stuck or something like that.

But it seems to work, I disconnected the cable to it and the light was still on. So i shortcurcuit it to see if I got a better result in the way to imitate the switch function.
Still the lights was on...
So I looked in the haynes manual, to see what fuse that the brake light uses...
Fuse no 1. I removed it and still the light was on!
When I use the brake a slight change of illuminity is noticed but just barely. There for I suspect that it is not the brake.

Last thing I made was adding a superchip. Can that be an issue?

 

[MrShorty]

Superchip shouldn't make a difference, since the EEC-IV system doesn't have anything to do with the brakes, except monitoring the brake on/off switch.

I once put the light bulb in backwards, which caused the brake lights to come on whenver the tail lights were on.

Beyond that, I think this is a case where you need to get a wiring diagram and simply trace wires until you find the short to power.

 

[DeRocha]

Ummmm are you low on brake fluid? The brake light comes on if the E-brake switch is triggered or the fluid level is low...

 

[JDraper]

If you're not low on brake fluid, and the e-brake isn't sticking, it might be time to flush the system. The older X's seem quite sensitive to having moisture in the brake fluid. When the fluid gets too much moisture in it, the specific gravity of the fluid changes, and the pressure sensor thinks the pressure is low, which kicks on the light.

 

[Peter Westling]

Thankyou for the replys. Since I disconnect the switch and shortcurquit it and that switch is the only sensor that tells that you press the brake then the fluid level shouldnt matter..? Or am I wrong here? What is the e-brake? I had low fluid level some months ago but I have refilled...

I will check the fluid levels again and check the light bulb placement.
Jdraper: Are you talking about the light on the panel or the lightbulb (The one that I mean) in the back of the vehicle?

 

[JDraper]

It will turn on the light on the dashboard.

 

[Peter Westling]

Ah, I am talking about the light in the rear of the vehicle, sorry for the english here... Referred to the haynes manual the mentioned it as "stop lamp switch" and "stop lamp".
Anyway, its the light that the car behind you sees...

The light on the dashboard is normal. No strange things there.

 

[ozx]

i bought two smashed up explorers, the body of a 97 XLT and the body and chassis of a 99xlt. i rewired the 97 with the harness' from the 99. Everything works except for a few things on the tailgate like the brake lights and the rear wiper. the tail lights come on when the headlights are turned on but it keeps shorting out. does anyone have a wiring diagram that i could use to fix this problem?

 

[Peter Westling]

I have a wiring diagram for my 1st gen. You'll find it in the Haynes book for yours too.
Kind of embaraced about the solution of my issue... both of the bulbs where turned 180 backwards... I didnt check that cause I never believed that I would do that mistake.. But I did. Anyway its working now...