I had to replace the ABS speed sensor in the rear axle of my Dakota. I had to remove the diff cover to clear out the remains of the last sensor. I refilled and used limited slip additive.This cleared the error but there is a new problem. The ABS pump cycles exactly between 10-15mph. It doesn't happen at any other time, it doesn't feel like the brakes are being applied, and there aren't any error lights or codes.

Any ideas on how to diagnose this?

Thanks

Does it cycle every time you slow down?

It uses a variable reluctor sensor which uses the tone ring (pressed onto the ring gear) to create a "sine-wave" that the ABS/RWAL module uses. At higher speeds the signal is very strong and very frequesnt. At lower speeds the signal gets weaker as does the frequency. If the signal goes to zero quickly vs. counting down to zero, the module will think the wheels have locked and will go into an ABS/RWAL cycle.

It is possible the new sensor is to far away from the tone ring causing the signal to drop from a low speed to zero. I do not remember the air gap between the sensor and the tone ring. You may need a service manual for that gap information.

Also, there is the possibility that as the old sensor came apart in the differential you could have chipped a tooth on the tone ring. You can see inside the sensor hole and spin the rear axle to make sure each tooth is present and accounted for. I do not know if the tone ring is a replaceable item or not?

Good Luck!

Yes it always happens exactly between 10-15 mph both accelerating & slowing. I'll see if I can get the sensor out without breaking it. I'll probably have to pull the cover anyhow to get a good look at the ring.

Thanks for the explanation

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01 Ram with Sure grip,
similar problem, my sensor was eaten alive.. I replaced it and at 60 MPH the ABS light would go on until I turned the ignition off and reset the system..
Bottom line problem was a very serious breakage in the sure grip that allowed large parts to hit and destroy the sensor and two teeth off the tone ring..
Tone ring is only serviced with the sure grip from Mopar.. or salvage yard parts..
I was able to repair mine (tone ring)using a MIG welder to weld new bumps on the ring and file them to match the others..
had to install a new sure grip as well..

some of the broken sure grip parts...

My sensor looked just like yours and I had to take the cover off to fish out the parts. I think its just annoying but my wife thinks its a safety risk. I'm getting the truck ready to give to my 16 yr old niece (it was previously my fathers). What do you folks think?

The Sure Grip wasn't working properly about the time that the sensor went. The rear wheels would chirp on tight corners. However since I replaced the fluid and put in some additive they haven't been chirping. I do have a 250 amp MIG so I could weld a new tooth if needed.

Tough call! If you grew up without the ABS/RWAL systems it would probably not be a big deal. But, if you are used to having ABS/RWAL you're not as mindful of the ass-end coming around on you during a rear wheel lock up.

If it were me & my niece I'd fix it.