Brake light keeps coming on

[reddahaydn]

Hi,

I've got a 2nd gen V6.

My brake light started coming on, faintly at first, then brghter and more often until it's pretty much always on now.

I've have the front brakes done a few months ago, the rear brakes done a month ago, and there's plenty of brake fluid.

Could it be a loose wire ot something?
I've searched and found other people have had these problems, but haven't been able to find a solution.

Any suggestions are appreciated

Cheers

 

[KidVermicious]

You've got a sensor in the top of the brake fluid cap. Check it and the wiring between it and the body harness. That'd be the first place I'd look, anyway.

 

[Footofgod]

Even if you are just a hair low on fluid, that light will come on. Make sure you are topped off.

 

[fourwd1]

There's another thing that triggers that light, the e-brake.
Make sure it is all the way off. But fluid level in the MC is the most likely cause.

 

[triggermann]

Like fourwd1 I would look at the e-brake push it in when your light comes on if it goes out bingo you found it.You might have to adjust the switch under the dash.

 

[reddahaydn]

ok fellas,
I've topped it up with fluid, i've looked at all the wires that I can see, I've moved the handbrake in and out and it doesn't make a difference (handbrake was also adjusted when the rear brakes were done).

I also had my brake joint look at it while they were doing a wheel alignment and they couldn't work it out.

Is the bulb hard to take out? Is there anything else it could be?

Thanks

 

[Footofgod]

ok fellas,
I've topped it up with fluid, i've looked at all the wires that I can see, I've moved the handbrake in and out and it doesn't make a difference (handbrake was also adjusted when the rear brakes were done).

I also had my brake joint look at it while they were doing a wheel alignment and they couldn't work it out.



Is the bulb hard to take out? Is there anything else it could be?

Thanks

If the light is on, something is wrong. Keep digging. Just taking the bulb out would not be intelligent.

 

[KidVermicious]

Ok, so attached to the underside of the brake fluid cap there's what looks like a float. I don't know for sure how it works, but I'm guessing when the float gets too low it closes a circuit and sends 12v through to the brake lamp. Unplug the cap from your harness, and mess around with a multimeter and see if you can measure any kind of resistance change through the harness when you raise and lower that float.

If it was stuck closed for whatever reason, that'd lead to your brake lamp illuminating.

 

[fourwd1]

If you just unplug the switch in the MC cap the light will go out if that switch is the problem.

 

[reddahaydn]

Maybe the side oftye float has some gunk on it and like you mentioned, it could be sticking down.
I'll give it a clean this weekend and see what I can work out.
Cheers

 

[Gerdo]

Or that the float is sinking.

 

[Rando92]

Start unplugging

Fourwd1 is on the right track. When the light's on, unplug the master cylinder level sensor. If the light goes out, there's your problem. If not, plug it in and try the same with the parking brake switch. It will be one of the 2. Once you find it, you just need to determine if it's stuck/out of adjustment, or shorted.

Often, the level float gets stuck, and the master cylinder reservoir just needs a few sharp (but not too hard!) whacks with a screw driver handle to be dislodged.

If it's not either of those, you need to start chasing a short to ground in the bulb circuit.