This truck came equipped with Rear only ABS. The dash light is staying on. I changed the rear axle sensor to no avail.

I can't tell if the ABS is working. Never really could but would like to try and solve the problem. If there really is any.

What next might I check?

Brakes are all working fine.

 

My 91s light stayed on and it ended up being a valve that is located on the drivers side frame rail between the rear tire and drivers door.