03 2500 ABS Question

[jelag]

My BIL's 2500 truck just had new tires installed...



We don't have a clue what kind of brake inspection was done when the tires were installed... We've been under the truck and find nothing loose and the ABS cables and connections tight and in place but we suspect that something occurred during the inspection to trigger this... A damaged Sensor cable etc... . please read on... .



As he turns a corner the ABS light comes on and the chime lets us know the light is on... as soon as the truck goes back to straight ahead the light goes off and the chime quits.



If he touches the brake when the ABS light is lite the ABS takes control of the stop. If the ABS light is off the truck functions normally...



We (he & I) think that we have a bad wire or sensor in a front wheel and the ABS system sees no signal so the computer thinks the tire is skidding and turns on the ABS during a slow down...



We don't have a clue how to test the sensor when its UN-plugged... Will a digital VOM read any kind of signal off the sensor when the wheel is spun to try and identify which wheel... .



I have a higher end code readier... will the code reader connected to the truck while driving give us any information when the fault occurs...



We have extra hubs and sensors but it requires pulling the Tire, Caliper, Rotor to change out the sensor... really a PITA... but we could start to just swap parts...



But I was taught by some really great guys 40 years ago to TEST, DON'T GUESS... and that's what I want to do...



Your thoughts please...

 

[HOBrian]

Can you put the truck in the air and take off all four wheels? Thinking out loud here... Put the truck in 4wd and 1st gear and see if you can see any binding of the ABS cables while turning from left to right, you might be able to pin point what is wrong.

 

[rscurtis]

You can ohm out the sensors for a complete circuit from the controller connections. That's how I troubleshot my truck when the ABS light was on (due to a damaged sensor). If you need the wire colors let me know and I'll look them up.

 

[CPittman]

Do you have a failing wheel bearing that may have damaged the sensor?

 

[jelag]

This is my BIL's truck and he tells me that the hubs were changed 30-40K miles ago. We were in the truck yesterday for about 120 miles and I felt no problems... I've got a set of hubs on the shelf in case we need them. . I was more or less looking for the ability to test this... As soon as the rain stops we're going to get the DVOM out and see what we can run down before we have to take it apart... We can't see where we can pull the sensor's without the removal of the rotor and that that entails...

 

[Bob4x4]

The front sensors have a connector on the inside of the plastic fender liner up about an inch.

The abs doesnt lock up a wheel when a sensor goes open and I have never seen it happen with a shorted sensor.

 

[Bob4x4]

Front sensors should be between 1800-2200 ohms rears 1600-2300

 

[jelag]

Truck fixed... we found that the left front sensor was going open as the truck turned. . The hubs and senors were replaced 35K miles ago and the sensor leads we're correctly routed... We raised the truck and we could pull on the drivers side lead and we could cause the ABS Light to come on and go off by pulling on the lead... . the open seemed to be within about 6-7 from the hub... .

Since I had a hub on the shelf we just replaced the hub... This is the first sensor only problem I've seen... once off the truck we were able to put an ohm meter on the sensor and pull on the sensor and the ohm meter would go to infinity...

He had purchased the hubs and installation back east 14 months ago...

Guys, thanks for the input on testing, and the other thoughts.....