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Brake warning light on dash

I have a 97 grand Cherokee that I just replaced the brake pads on. And the brake warning light is on on the dash. Brake fluid is full. And when I depress the bake to stop the warning light goes off. Then on after releasing the brake. Any idea what the problem is??

wonder if your e-brake handle is all the way down or needs adjusting

It’s all the way down. I’ve even slammed it down to make sure. As I said when I stop the brake warning light goes away then comes back on after letting go out f the brake.

Well in my two experiences, you can make doubly sure that the switch activated by the emergency brake is not out of adjustment or disconnect as a test. The other one though my Olds had a malfunctioning switch in the master cylinder. Unfortunately the master had to be replaced to replace the switch. Maybe try disconnecting the switch as a test to see which one is activating the light. Given the symptoms sounds like it is the one in the master. Maybe some dirt or something got in it if you retracted the brake pads without opening the bleeder. Main thing I guess is you have brakes.

From what I see the brake warning light (as opposed to the ABS warning light) turns on b/c

  • the parking brake is engaged; or
  • there’s unequal pressure between the two (front & rear) hydraulic circuits

I expect in your case it is the latter, unequal pressure. Most likely air in the brake lines, low brake fluid, or a leak. I’d start by bleeding the air from the brake lines again.

Another idea, less likely to be the cause, but when changing pads in ABS equipped vehicles the recommendation here is usually to open the caliper’s bleeder screw before pushing the piston back in to make room for the thicker new pads. Otherwise brake fluid can get pushed backward into the ABS controller.

I did unplug the sensor and the light went off. As I plugged it back up it still had the warning light. And yes I have pressure on my brakes and can stop fine.

Thank you. I will bleed the brakes again to make sure there isn’t air in the lines. I’ll get back to you once done

Also before I changed the pads. The light was on. I thought maybe worn pads. But upon replacing them all my pads were only half worn.

Ok, so the warning light was already on before you replaced the pads. … hmm … from what I see the switch that tells the computer that the rear/front pressures are different is in the brake proportioning/combination valve. If you are certain there’s no air in the lines or leaks, you may have to replace that part. It is probably possible for a shop to test that switch in situ, at least to the extent to tell if that switch is causing the problem. It should either make a low ohm connection or an open connection (not sure which) absent any hydraulic system fault. If you could verify it was switching from one to the other when you pressed on the brake pedal, you’d at least know the problem was the switch was actually switching and not the body control module. A problematic connection from that switch to the body control module could cause this too. Or a faulty body control module. Do you have a wiring diagram for the brake warning system? That would probably tell you if it is normally open, or normally closed. The combination valve is often close to, usually under the brake master cylinder. There should be an electrical connector on it, which is for the switch.