My dash brake warning light keeps coming on. Anybody know what could cause that? It comes on for a few seconds then goes away, then comes on a little while later. Fluid is full, and it has a new vacuum pump. Sometimes it flutters too.

 

If your vacuum pump is new and there is plenty of fluid Id say check the switch at your ebrake. Try pulling up on your pedal or look to see if the plunger is being pushed completely. If there is any excess slack either your rear brakes are out of adjustment or the cables are stretched. they supply the tension back the peadl to make sure it returns all the way to the top.

 

Check for vacuum leaks.
If good replace vacuum switch.

Bill

 

Mine does the same thing. I might have to replace the back brakes. It's been forever.Maybe never.Thanks Oversize

 

Do the back brakes have a sensor on them. I will need them in the next 10k miles. I put new front ones in about 6 months ago, and that didnt solve the dash light problem.

 

There's no separate sensor on the rear brakes that turns on the dash light. It's driven by the switch on the master cylinder (hydraulics), the vacuum switch (boost) and the parking brake pedal/arm.

 

Hmm, maybe I will replace all three sensors.

 

To what end?

Maybe you really DO have insufficient vacuum. Maybe there really IS a problem with the hydraulics. Maybe the parking brake really IS engaged. Even if NONE of the above are the case, TESTING each one rather than throwing parts at the problem will be MUCH cheaper. You can buy two or three multimeters for the price of any one of these sensors/switches.

 

Check fuse number 15 (antilock brake) in the under dash fuse box. I was pulling a trairer with faulty wireing and it popped that fuse, and the dash light would come on.

 

Well I am on the second vacuum pump in less than a year. The fluid level is good and full. The parking brake works perfect and shuts the light off every time, and the brakes work perfect. It just randomly will come on, sometime killing my cruz control, sometimes just sitting at a stop light. No reason, just does.

 

Ah, NOW we're getting somewhere. The common point is the hydraulics. If it's happening even when you're not braking, that pretty-much rules out the vacuum issue. And a problem with the parking brake switch wouldn't have any impact on the cruise. So that narrows it down to the hydraulics. Maybe the switch/sensor associated with the recall is bad, maybe you have an actual hydraulic problem (external leak, failing M/C).

 

A fluid leak causing the master cylinder to go low is supposed to set off the red brake light and the ABS light.

The parking brake is the most common thing to mess with the red light by itself.
If the cruise is effected and you are getting a brake light then you have a brake light either shorted or a bulb out. If you are on the cruise and it kicks off when you flip the turn signal then you have a bulb out too.

How far down do you push your pedal when you stop? Does it feel spongy at all? If it goes down consistently more than an inch or two then adjust up your rear brakes. Your park brake pedal really shouldn't go down more than half to 2/3 of the way either. If more adjust your rear brakes.

Another common thing I've seen is contaminated fluid causing this. If yours is real dark then suck it out with your wifes turkey baster and replace it. Then bleed the brakes good. Brake fuid collects moisture like crazy and that's not good anywhere in the system.

 

I just reread this. Go check your trailer wiring in the back. I think you have a short on the brake light circuit. Maybe water in the conduit or something. If you got uhaul crap connectors back there I can almost guarantee it.

Cruise effected nearly always means the brake lights are shorted somehow or burned out. Or even just loose in the socket.

 

Trailer wiring issues only affect the brake lights on the bed and the cab roof, not the dash warning light. The sensors/switches on the M/C are what's common between the cruise and the dash light. Well, actually, another common point might be the RABS, in the (rear) diff. But I would think the ABS light would be on as well. Does the ABS light come on with the "key-on" bulb check? Is the speedometer flaky?

 

I think it is hydrolic related too. The brakes work perfect, I pull heavy trailers and even with them I hardly have to push on the pedal. The fluid has never gone down in the 45k I have had the truck. The only thing is is, that it is somewhat dark. I am planning on changing the fluid when I do the rear brakes in a month or so. I don't think it is a brake light switch, they always work with out a hick-up, and i never have problems with the trailer brake lights too. The trailer brake lights are on a different system I think anyway. It has the factory tow package, so all the trailer wiring is separate from the truck brake wiring.