my parking brake light is always on. The mechanical part of it is working fine. Its engaging and disengaging. Its just that the light on the dash board is always on. It just started turning on while I was driving on the road. Could it be a fuse or a relay?

 

Check your brake fluid level. If it is low, that light will come on. If the fuid level is ok, and the switch is ok, check the p/b switch

 

parking brake switches are usually normally open and go closed when the brake is engaged, the brake handle going up releases the switch and then presses it back down when you put the brake handle down, 9 out of 10 times the switch gets pushed to the side or broken so when you put the brake handle down it does not push the switch down. this would be the first place I would look.

 

The parking brake light is also an indication of a problem with the brake system. I think a low fluid level is more likely the problem than the switch Rover Chris mentioned.

As a general rule, any red lights displaying on the dash means don't drive the vehicle.

 

if you have a meter I would test the wires at the brake fluid reservoir, this will tell you if that is why your light is on, if that is ok and not why check the output of the parking brake switch, these 2 tests will take about 10 - 15 minutes and you should find your problem, also what year is your disco?

 

I have the same issue with my '03 Disco II. What voltages do you look for at the float switch and parking brake switch? The parking brake switch just seems like a grounding switch to me, is that true?

Thanks.

 

yes the parking brake switch will actually rest at +12v and go to ground when the handle is pulled up, as for the brake fluid sensor I would imagine it would be the same as the parking brake switch (I haven't looked at it but it should be), ground going in on 1 wire and the other wire will rest at 12V+ and go to ground when the fluid is to low.

just so you understand what you are looking at +12 volts goes through the bulb (back feeds while it is off) and goes to the switch, so when you test this wire you will see +12 volts then when these switches are activated ground goes to this side of the bulb and the positive on the other side will turn the light on.

Sorry I know I explain this stuff too much but for me, I have to understand how the whole system works in order to troubleshoot it.

 

Thanks got it working again. I think it was the brake fluid reservoir sensor. thanks guys.

 

Had this problem a few weeks ago, my mech. replace the brake master cylinder, it was leaking... this is not hard to do yourself if the cylinder is leaking.