DTC 28

R/R Wheel Speed Acceleration Fault:

Circuit Diagram:

RIGHT REAR WHEEL SPEED ACCELERATION
The rear wheel speed sensors monitor the speed of each wheel by placing a magnetic coupling next to a toothed ring mounted in the hub and bearing assembly. The signal changes with the wheel speed. If the ABS module sees wheel speed signal change over 16 km/h (10 mph) in 8 milliseconds while the car is moving, the control module will disable all ABS and turn On the antilock telltale.

CODE PARAMETERS
Code 28 sets if:
^ R/R wheel speed changes by more than 16 km/h (10 mph) in 8 milliseconds.
^ This code can set anytime the vehicle is moving and not in ABS braking.
^ This code may set in conjunction with code 24.
^ The vehicle should be driven at speeds above 64 km/h (40 mph) to check for reoccurrence of this failure.

DIAGNOSTIC AIDS
Before proceeding with the trouble tree, make a thorough visual inspection of the wheel speed sensor circuitry. Closely inspect the inline connector(s) since this is the most likely area for opens or shorts.

Connect the Scan tool, spin the wheel by hand, and monitor the wheel speed. Make a comparison with other wheels.
^ Visually inspect sensors and connectors. Check the wheel speed sensor for damage.
^ Using an ohmmeter to check resistance, shake wires to locate intermittents. For sensor resistance, refer to the resistance chart.

Check the tightness of the female terminal grip with a spare male terminal.

When attempting to diagnose an intermittent problem, use the Scan tool (select Malfunction History from Scan tool ABS menu) to review supplemental diagnostic information. The supplemental data can be used to duplicate the problem.

Check bearing end play. End play can cause this code to set. Measure end play using a dial indicator positioned at the center of the bearing spindle. Pull in and out on the spindle, do not rock it. Bearing with end play measurements greater than 0.10 mm (0.004 in.) should be replaced.