My ABS, EPS, and EPS/BAS lights would come on after wheeling in mud, but it would clear up after a good pressure washing. This time they stayed on. In addition to the lights, it sometimes tries to "help" me drive by locking up the left rear wheel at low speed.

I have seen a few related topics and I am pretty sure I have at least one wheel sensor that isn't functioning (mud & sand in bearing, broken wire, bad sensor).

The question is which wheel sensor is bad? How can I figure out which wheel(s) aren't working?

If I borrow a scan tool, will it tell me which sensors aren't sending data?
-wwiifirearms

(The dealer basically took one look at my lifted rig on 35's (with signs of use) and said it was packed with mud and wasn't covered.)

 

It is on my list of things to try, but was hoping to first narrow down which sensor was the issue.

I took the front apart, pulled the calipers and rotors, removed the sensors to look for damage, but didn't unplug them.

Sounds silly but I wasn't sure I could figure out the little plastic clip without breaking it. I knew if I broke it I would have no chance at getting any dealer to warrenty.
-wwiifirearms

 

mine did this and ended up being broken abs clip on the rear, but u could see that it was broke.

 

ive got the same problem. always went away after a big power wash.... this time not happening. ive got the weekend off so i plan on checking it out. starting with the battery disconnect then going from there.....

 

FYI. I tried Disconecting the batt. and then leaving the key on for 30 sec. , but it didn't reset the lights. -wwiifirearms

 

There are tone rings on the outside of the shafts that look like a bicycle spoke where the chain rides...

The notches on the tone ring are used to create differing e-mag pulses as they pass in front of the magnets in the ABS sensonrs. If the tone rings are full of mud and the sensor can't "sence" the tone ring it will cause problems. The other possiblity is that the mud has pushed the sensor back away from the tone ring and once you pressure wash it the mud gets removed from between the sensor and the tone ring allowing it to do it's job again.

The rear tone ring is likely more suspect as the sensor is much longer and has the e-brake setup on the back side of the rotor to allow mud to build up and cause problems.

Hope this helps.

P.S. I HATE mud for this and many other reasons...

 

Thanks! That definately helps. I had seen tone rings mentioned in another post, but until you explained them I didn't really know what they were or how mud could impact them. It definately makes sense.

I could not do as good a job pressure washing this time b/c it is 17 degrees outside.

Can I get at the tone ring to see if it is jammed with mud? I have no problem pulling off the brakes and sensor, but I would like to stop short of pulling the dif, bearings, or axles.

Anyone have an exploded diagram of this set-up?

Thanks,
wwiifirearms

 

I took the rear brakes off to expose the tone rings and they were covered in mud. There were small pebbles jammed in the tone rings, which scratched up the sensors pretty good.

I removed the sensors and cleaned everything, including unplugging an cleaning the contacts. This was actually an easier job than I imagined.

I drove it about 10 minutes and the lights are still on.
Maybe I will get lucky and they will now turn off with more driving.

Do you think the scratches on the face of the sensors will stop them from working? Anyone have a good source for new sensors?

I haven't looked into what it will take to get to the front tone rings, but they seemed pretty well sealed. That maybe next.

-wwiifirearms

 

If you check the code via the "turning the ignition key to the on position 3 times" way, it'll show you the code on the dash. Then, reference it with the code chart here on the Tech section.

You probably have a bad speed sensor. I've replaced them about 3-4 times already and just received a batch of them to my house. They are about $50 for all 4 corners. They've been going out on me lately when fording mud and what not.

 

I replaced broken ABS sensors on the front axle. My lights were off for a while, but now they have come back on and have been on for a while. It does try to help me drive briefly when I first turn it on.

I'll be taking it to the dealer to find out what's going on with it. Something if effed up.