ABS & TRACS Codes
If your 850 and later model vehicle has an ABS/Tracs light on then “you’ve got codes”.
A common failure for the Teves system is the control unit itself and can set a number of codes including 123-124-213-214-313-314-323-324 for the rear wheel speed sensors, namely the right side. Don’t confuse these with codes 141-142 for the pedal position sensor which also has a somewhat high failure rate. Later version 850’s, namely 95 and up through the 70 series, used mostly Teves control units. 93-94 850’s used ATE control units.
Before starting anything be sure to check for physical damage of the wheel speed sensor, the pulse ring, and the wiring. Be sure no debris like sticks, rocks, or rope has damaged the wire to the sensor. To test your wheel speed sensors, disconnect the main harness connector from the ABS unit and find the pins for the wheel speed sensor fault you have. LF = pin 11 & 4, RF = pin 18 & 3, LR = pin 2 & 10, RR = pin 1 &17
Using a digital Volt/Ohm meter measure the resistance between the pins with the key off. The reading should be between 1040ohms and 1160 ohms. With the key on check for voltage between pin 8 and pins 4,3,11,18 the reading should be around 2-3 volts. Have a helper rotate the wheel while you monitor the volt reading, you should see a changing/pulsing voltage as the wheel is rotated. If your sensors have the correct ohm value and the voltage output is correct, chances are you need a control module.
In some cases when the ABS/Tracs light is on yet there are no codes, you may have a bad ignition switch. With the vehicle running, jiggle the key back and forth in the ignition and look for the lights to come on, if they do you will need to replace the ignition switch.