hey and thanks for reading my post, anyways i have a 97 x-cab and my brake light seems to be coming on, but only when i pump the brakes... like when i'm going into my driveway and i'm judt feathering them to get the truck into place... and the light only comes on for a short time.... i thought that there might have been some air in the system (i just changes the brakes), so i bleed them off again... but i'm still having the same issue. i was wondering if it wossible that the sensor might have been screwed up... of if there was something else that i may have missed.... thanks in advance...



Robbgt

 

Is the pedal going down farther than normal? Low on brake fluid? If the mastercylinder is leaking, it will leak into the power booster. You can pull the M/C from the booster (without disconnecting lines) and see if there is fluid comming out at the piston into the booster. Just a thought.

 

BUMP from way back... The problem jumped back today.... the brake light only comes on at low Rpm's, and when i'm pumping the brakes, say to pull into a parking space.... The light will come on momentarily, but when i rev the engine it goes away.... all fluids are fine and I re-blead the brakes today, but it's still happening.... do you think it might be the Vacume pump?....and is there a way to test to see if it is the pump? The petal does not travel any farther than normal, same feel (not squishy or firmer than normal) and the brakes also work perfectly, thanks in advance

-Robb

 

Thats what mine did right before the Vac. Pump died. but the light would just come on and stay there till i accelerated, then go out. Finally one day the brake pedal got real hard and thats when I knew the pump was dieing for sure, it had gotten real loud too, like a lifter tick, if you know how that sounds.

Save up, there spendy little buggers, like $150 i recall, or somewhere in that area. real easy to change out, three bolts, just need to have the pulley pressed off and on.


Diesel Rod

 

sounds like its dieing. mine did the same also. kinda makes a hooting noise when you pump the brakes fast?? powersteering pump puller and installer works good on the pulley

 

Thanks! I had an idea.... do you think it might be because a vaccume leak in one of the lines? Mine are still the original ones, and they appear kind of grungey and beat up.... I'm not sure if the brake light would sense a vaccume leak or not.... But i thought that when i rev it, the light goes away, and when i pump mthe breaks it comes back, it could be just as simple as a leak in one of the lines (or i'm hoping it's this simple!!) thanks!

Barebackjake, No strange sound, just the normal "Fluidy/coompressiony" sound that it normally makes.... hopeing it's just the vaccume leak....

 

You light should come on IF you pump the brakes and the engine is off, or if there is no vacume thats why it comes on when you start the truck, once the vacume is up it goes out, so you could have a leak, but I would guess a pump over a leak cuz mine went out at 195,000 and all the line are original. you could put a vac gauge on it and see what it does, my new one will peg out a 30" gauge at idle, I couldn't tell ya what there supposed to be.


Diesel Rod

 

thanks a bunch, I'm gonna try the vac gauge on there just to check and see what kind of pressure it's putting out.... ALSO, is it possible/likely for the manifold where all the lines connect up to, (where the vac feeds in from pump, and lined out) to be cracked/leaking from anywhere in there from normal use?? Truck only has 58K on it, so you might be right that is just the pump that's shot. I just went out and put my (air leak specialised tool, A.K.A. my hand) down by that air manifold, and it felt that there was some air escaping, but i might be crazy.....

 

I cheap as that nifty tool is, there pretty good and useful.

as for the air thats "escaping" thats prolly just from the fan, cuz if there is air blowing out then you definetly have a problem, cuz its supposed to be a vacume, and you wouldn't feel anything, any hear it, and thats near impossible with a diesel engine rigth there.

Diesel Rod

 

darn, and i was hopeing that it was just a simple leak... guess i will have to put the gauges on hold again and spend the cash on a vaccume pump, any sugestions on where to pick one up rellatively cheap+good quality like autozone?? (I ain't going to the stealership) thanks -Robb

 

UPDATE: Ok, so now i have the new pump in, and the brakes are working ok most of the time.... I am getting a "hooting" sound from the cabin area when i pump the brakes not sure what the deal is..... BUT the bigger problem is this.... now when i start up the truck, especialy on a day when it's damp outside, and i touch the brakes after i'm rolling, they lock.... I can't tell if it's the front or back, but i would guess front because the truck lunges forward when they do lock up.... It goes away after a few complete LOCK cycles, and i get my normal brakes back..... So what else could it be??? Master cyl, Proportining valve, or brake booster???? or is it something else??? thanks for the help.....

-Robb

 

i think i'll give this topic a little BUMP.... the post before this has all the questions... thanks!!

-Robb

 

have you replaced the little valve thats on the booster where the vac line goes too?? i replaced mine and it cleared up the damp cold wet grabbyness

 

Going to NAPA to grab one today.... i'll give that a shot, thanks barebackjake.

-Robb

 

So how is it now, my parents '93 will lock the rear passenger tire if your on snow anytime, I just assumed it wasn't set up right, or a proportioning valve was sticking. it will sometimes do it on dry tar if you hit it hard enough. where did you end up getting the pump at, and did the check valve on the booster fix it???



Diesel Rod