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ok so recently when ive had to stop pretty quick my brake light comes on along with the abs... at first it would come on for a minute or two and then go away ... but the the other day i was pulling my trailer and had to come to a quick stop.... n the light came on n i pulled in to a gas station and waited a minute but then it seemed like the rear brakes got stuck because i was only able to move it with my 4wheel drive on so i got under the truck and adjusted to the point were it seemed to brake lose ... and ever since then when i do stop my brake and abs light come on and stay on for a while .... so my question is there a sensor of some sort that i can change out or does this mean its time to change out the rear brakes.
But its not leaking oil ...so i dont belive its my brake master cylinder
The VSS sensor for the ABS is on top of the rear differential, its harness is attached to either the e-brake cable or the brake hose so just follow that and you'll find it. Has the truck been shifting funny tho? Cause the speedometer and the PCM for the trans use the same VSS for their function, and if the VSS was going bad there would be a whole lot more weird things happening than just the ABS light.
The rear brakes holding on may point to a bad rear flexi brake hose. Both lights on together may be due to low fluid level, dirty/loose wiring connector at the master cylinder or a defective brake fluid level sensor.
I take it that your vacuum pump is good.
Check brake fluid level first.
ok so jus because i figured it wasnt that expensive i bought the vss ,but i dont belive it was at all related to my problem...
Now that i try to press my e brake it doesnt work so it almost seems like my rear brakes arent working like they should be i read somewere that there was a valve of some sort mounted to the driverside frame rail which i did find and some say to take out a bung and remove a spring and to see if maybe something cloged the line... jus wanted to see what other advise i can get....
and the truck is a 94 f350 with a 7.3 5spd with a hydroboost setup so i have no need for vaccum atleast for the brakes...... im not sure if i sould be focusing on the rear brakes themselfs the brake master clynder or that valve...
ok so i did the rear brakes and wow yeah one side was cracked and no good the other had no brake pad left and the adjuster piece was out of place... so they were completely shot. so now that i i did this i figured the "brake abs" light turn off but still hasnt.... so im jus wondering were do i go from here .... What are common symptoms of a brake master cylinder faliure?
list of items replaced: abs sensor, brake light switch, and rear brake shoes with new hardware and adjuster.
so whats next...?
What you don't want to do is keep throwing parts at it...
From what I know, if your truck's ABS light is on then you should have a trouble code stored in the rabbs control module. You need a scan tool to find and clear the trouble code, and a manual to find the problem and fix it. It may just need to have the code cleared... but I cant say for sure as I'm not too familiar with your truck.
Some common symptoms of a bad master cylinder are: having it fade away under light application, having signs of leaking ether in the cab or in front of the booster, or having no or little brakes after everything else is known to be good.
To answer ur question dave the truck does brake alot better but yet it doesnt feel like before when i had just added the hydro boost... were u would just lightly tab the brake and would feel firm ... it now it doesnt it will feel that way one moment and then the next feel a bit more mushy i guess or soft . Again it could just be me thinking to much about it.
And the thing is the brake /abs light comes on and will not go away until u turn of the truck and turn it on again ... but wont come back instantly but after u hit the brake and hold on it for a few seconds then it will come up again.
When you are working on a RABS truck, there is a specific bleed procedure to follow.
I can't remember if the RABS unit was before the rear wheels or after.
I wonder if you have air in the system somewhere?
Or possibly the rear bleed procedure was not followed last time it was bled.