So I recently replaced all four ball joints on my disco. As soon as I started the vehicle I got lights every where. Scanned and got codes for both front wheel speed sensors erratic and one for low signal. Took it back apart and every thing looked fine, but since I had an extra set of sensors from a parts car I replaced both front sensors. Cleared the codes, started it up and bam, the lights came back without even moving the car. Drove the car and the sensors read just fine on the scan tool live data, checked the resistance of each sensor from the module good, 950-1050 ohms. Swapped the SLABS with an extra and still got the lights with out even moving the truck. Cleared codes, still came back on with out moving. Good power and ground at the SLABS. I am all out of ideas.

When I start it after clearing codes, the lights will come on with in a minute with out even moving the truck, but won't show codes. When I drive it, it will set the same wheel speed sensor codes. But if it really was a wheel speed sensor erratic issue, why do they come right back on without driving the truck? If it was an open circuit that would make sense but the codes are for erratic signal which shouldn't be an issue on a stationary truck.

Any one have any bright ideas?

 

Have your hubs been replaced?

 

Your sensors must mate the hub manufacturer they came with. If you install an aftermarket hub with an OeM sensor. You would more then Likely have an incorrect gap causing erratic signal. The sensor is a magnet - which reads the teeth in the hub ring with magnetic current.

if you have debris on sensor from installing, (or crumbling failing hub) this would cause fault.
if you forgot the O-ring gasket installing - this could change elevation of sensor & cause fault.
same principle with mis matched sensors.

usually