New wheel sensor reads bad...ABS Module bad?

08 Crew Max with 243,000 miles on it. All the Christmas lights came on...ABS solid, traction control solid, VCS flashing, 4hi/4lo flashing. This happened last January and we changed the right rear wheel sensor and the wiring harness for both sides. This time the diagnostic said left rear wheel sensor so checked and double checked, sensor bad. Changed out sensor, cannot clear codes. Checked sensor again all sensors good but diagnostic cannot see the left rear sensor still so lights remain. Checked that wires have power from back of truck to the big bundle of wires under the hood on the passenger side of the truck. ABS module bad? The 80 point pin is not numbered. I need a schematic for the pins so I can check module has power. Does anyone have that schematic? Is it worth the $2000 part? I have seen several on eBay for less than $200. Any other things I should check?

 

So you've swapped the sensors from side to side and the code stays back left?

If you have access to a scope, you can chock your front wheels, put the truck in neutral, jack up that rear left wheel, then spin it by hand and see what the waveform looks like coming out of the sensor:
https://www.picoauto.com/library/automotive-guided-tests/road-speed-sensor/

Some things that come to mind with your situation...

There could be something garbling up the waveform in the ABS module. If you get crappy waveform with everything all hooked up (back probing the speed sensor), try unplugging the VSS at the axle. If the output of the sensor suddenly does what it's supposed to, hook it back up at the axle and unplug it at the ABS computer. If the waveform still looks good, then there's something amiss with the ABS module. If the waveform looks bad with the cable going into the ABS module unplugged but is OK with the VSS unplugged at the axle, then you have a wiring issue between the axle and the ABS module, and no amount of parts swapping will deal with that (this is where a dealership will tend to screw up and not take the time for proper diagnosis). In the case of damaged wiring like this, you will have to follow it from the ABS module to the axle and look for spots where it's chafed, pinched, or unnaturally bent.

If the waveform is still garbled when the sensor is unplugged at the axle, that would suggest a sensor problem or potentially schmoo on the rotor/gear on the axle itself. In this case you could pop the axle out of the diff and clean it off and you may be in business. If this ends up being the case, you may want to consider a fresh wheel bearing back there.