So I have a similar problem to some of the guys here, I get the abs light and brake light coming on when I start it, but its only irregularly. It stays on right when its started to when its shut off. but sometimes when I restart it, theres no issue. very irregular.

 

Hi All, Got a similar question on 2001 Dodge Ram 2500 4X4...150K miles.. Recently the ABS Light and Brake light came on and the brake peddle got real stiff for a few seconds... These Lights now are going on and off periodically.. few minutes on, then few minutes off while driving... most time the Brakes work fine but once in a while while light is going on or off brake gets real stiff again... then they work fine again..any ideas what could be the cause?

 

Check the vacuum line to the brake booster. If pedal gets stiff suddenly, there mayu not be enough vacuum to the booster.

 

What engine?

 

Hi HeyYou, I got a 5.9 Diesel on the ABS and Brake light on... Also, from looking thru threads I should tall you that my Speedometer is workign fine... Just sporadic ABS and Brake light going on and off and occasionally the brake gets real hard and the truck doesn't stop too well... gotta really step on it.. then it lets up and everything is fine again.. until next time, which can be an hour or a week. Brake fluid is full and brakes might be on the low side but not wasted.. Any thoughts?

 

BTW... Stiff peddel always happens during a shift between lights coming on or off... Like the ABS is kicking in...

 

Or like the vacuum is changing with rpm change........when it shifts......like there is not enough vacuum.......check for leaks....or don't.

 

Put your truck info in your sig, us old guys can't remember what year ya got.

Do you have 4wal? Or just Rwal? Given you have a diesel, do you have a vacuum booster, or hydraboost? If a vacuum booster, is there a vacuum pump on the motor? (I don't know as much as I would like about the oil burners in these.)

 

Truck info.. 2001 Ram 2500 4X4 5.9 Deisel, 5 Speed manual... 4 Wheel ABS, Disc Brakes all around... not sure about all the vacum booster info as I'm not overly mechanical...

More info: When brake gets hard it starts to pulsate like the ABS is kicking in and the truck doesn't stop unless I stand on the brake! Heavy truck... right. Then it goes back to normal and I'm good for a while...

Also, Sorry for the confusion... the Shift between lights was in reference to when the ABS and Brake light comes on/off...not shifting the tranny...I will look for leaks in the vacume line though.. Just need to figure out where that is and what I'm looking for?

I took it ot a small shop and they ran a scanner on the truck said Code was showing front left ABS speed sensor... but then they said the Tech also thinks it's a bad ABS Control Mod... Like $1000 quote to work on the truck... with all the mis diagnostics I wanted other opinions before I shell out a grand to a shop that does mostly oil changes and brakes>>>

 

Wheel speed sensors are relatively easy to change, I would recommend dealing with that first.

Looking in the manual, seems der diesel uses the hydra-boost system. No vacuum required. Diagnostics say to start the engine, crank the wheels from lock to lock a couple times, shut off the engine, wait one hour, and then step on the pedal WITHOUT starting the engine, you should get two pedal presses with assist, before pedal effort starts going thru the roof. If you don't, replace the booster.

This assumes, of course, that the power steering pump (supplies hydraulic pressure for the brake booster) is working correctly, has the right amount/type of fluid, etc.