Hi all.

Son just came home for the holidays from college, and (as usual) there are a couple of new lights on.

On the the brake idiot light on the dash.

First, I assume that this light only provides status on the parking brake (right?).

If so, how would you recommend troubleshooting it?

I would guess it's the switch?

Is it located at the parking brake handle?

Or at the brake on the propeller shaft?

Thoughts on the best (read shortest) steps to diagnosis/fix this would be appreciated.

 

The brake warning light also comes on if the brake fluid level is low, or if there is a fault with the ABS system. Check the fluid level and read any ABS codes.

 

Here are all the Warning Lights & how they function. Go NUTZ!!!
It's not a matter of IF they will go on, it's just WHEN.

 

Fluid level in master cylinder is likely low, just enough that it occasionally lights the light. You likely have a leak between the master cylinder and reservoir (very common on truck older than 5 yrs). Eventually it will drop low enough to permanently remain on. Fill it and see if the read light goes away.

 

I've had a faulty cap and wiring plug set off the light before. Same conditions. Would come on and off

 

Low tire pressure or seized caliper has also triggered the light on mine.

 

Wow, thanks all for the responses, especially for the clarification that the brake idiot light does more than just tell you the parking brake is on.

Given the behavior: light seems to come on when accelerating from a stop or going up or down a grade, I am going with low brake fluid. Does it take DOT3 or 4?

When he had the 3 amigos a couple of years back, we threw part at it, including a shuttle(?) switch on the ABS unit, so guessing it's not ABS

Further the SES light isn't on (this would be on if the vehicle threw and actual code, right, even an ABS code?).

And never seen any leakage around the brake fluid reservoir.

And brakes stop straight and true: no sticky calipers or anything like that.

So I am going with the brake pad having finally worn sufficiently to drop the level in the reservoir just enough for the low fluid sensor to go on and off when it is sloshing around.

I'll check it once my son get back from rock climbing with his buddies out at enchanted rock here in the hill country of Texas and let you know what I find.

 

DOT 4. Does not light SES if it is an ABS fault. The leakage is hard to see, it is more of a seepage. Look at the metal part of the master cylinder, if the black paint is bubbling or gone, you have a leak. Run your finger across the bottom surface, if it comes back wet, you have a leak.

 

OK, brake fluid reservoir was a little low -- right on the min line -- so topped it up about halfway between min-max. No light so far so that looks like the issue.

No ABS trouble codes.

However, the black paint on top of the master cylinder is gone, though it is dry, i.e., no fluid present. Could it be that I have a leak bet. the reservoir and master cylinder but the heat under the hood burns it off?

If so, it is just a matter of replacing some o-rings/seals bet the reservoir and master cylinder?