What can make the Brake light come on?

[Atrus]

Driving today and my brake light came on. Stayed on for a good 15 mile drive. Pulled into the lot at work, turned the KJ off, restarted it, and it's off.

Is it only to sense when the parking brake is applied or when brake fluid is low? What else can cause it to kick on?

To give some background:

1) Replaced brake pads at all 4 corners a good 4-6 weeks ago. No issues until this morning.
2) Brake light popped on this morning while I was sliding on ice and pumping brakes.
3) I have no ABS/TCS at the moment (hence the sliding/pumping in #2) as they crapped out on me on Monday morning. My ESP/BAS, Traction, and ABS lights popped on Monday morning right as I parked the KJ. They did go off for about 3 miles yesterday (Tues) morning, but came right back on and have stayed on.

I am wondering if these two items- the ABS/TCS going kaput and the brake light - are related and if the brake light would shed more light on what could be causing the ABS/TCS problem. It's making me think rear axle issue, nothing wrong on the front axle.

 

[sleeve]

The brake light can kick on when there is an issue with the ABS system as well.

You could have a bum abs sensor.

 

[LibertyTC]

Atrus,
Have you ever flushed the brake fluid?
Did you recently change the calipers or do a bleed?

 

[Atrus]

never flushed the fluid....no caliper change...hydraulics have stayed 100% intact since it rolled off the line.

I did change pads once, but that's it.

Hopefully I can get out in the garage tonight and check it out.

 

[yellocoyote]

Check your wiring/plug that's above the rear diff (speed sensor?). I know it sounds like an oddball thing to say, but when the wiring started getting worn on that sensor on my kj, one of the first things that happened was the brake light came on. Then, eventually, other lights started coming on - ABS, CEL, etc.

Just a thought.

 

[Atrus]

Jayme - I don't have a speed sensor on my '07. My ABS sensors are my speed sensors

But, good call - I have heard that pre-2006 KJ's often have problems with that wiring.

 

[yellocoyote]

Jayme - I don't have a speed sensor on my '07. My ABS sensors are my speed sensors

Ah! Okay, I wasn't aware of that. You learn something new every day.

 

[jnaut]

Any codes?

 

[Atrus]

None that I can pull - I am sure there are ABS codes in there (have to be since the light is on), but most scanners (mine included) only scan PCM info...they can't retrieve ABS/TCS data and codes.

I may stop in at the Belle Tire near my house tomorrow night and see if they can give me a "free estimate"...if labor and parts are cheap, I'll have them fix it. I am guessing they won't be, so I'll repair it myself but at least I should know what sensor(s) are bad.