DTC 28

ABS Schematic: Code 28:

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 ABS and turn On the antilock telltale.

CODE PARAMETERS
Code 28 sets if:
^ RH 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 Chart: Code 28 (Part 1 Of 2):

Diagnostic Chart: Code 28 (Part 2 Of 2):

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.
^ ABS system is very sensitive to ring damage. Inserting screwdrivers, crowbars, etc. into the ring area and prying against the ring will cause damage.

Resistance-Temperature Table:

^ Using an ohmmeter to check resistance, shake wires to locate intermittent. For sensor resistance, refer to the previous chart.

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

^ The distance between the wheel speed sensor and wheel speed sensor ring should be between 0.60-1.78 mm (0.025-0.070 in.).

When Attempting To Diagnose - an intermittent problem, use the scan tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.

^ Select Malf History from scan tool ABS menu.

Intermittents Or Opens - suspected to be at the connectors can be detected by using a diagnostic service probe.