DTC 23

Fig. 112 Code 23: Right Front Wheel Speed Sensor Continuity Fault.:

DTC 23: Right Front Wheel Speed Sensor Continuity Fault:

CIRCUIT DESCRIPTION
As each wheel turns, the wheel speed sensor for that wheel creates a small AC voltage as a toothed sensor ring, mounted in the front integral hub/bearing assembly, is passed by the stationary sensor. The sensor consists of a permanent magnet and coil and generates voltage by magnetic induction. The frequency of the wheel speed sensor signal is proportional to wheel speed.

The EBTCM/EBCM uses the wheel speed sensor signal to calculate vehicle reference speeds and individual speed, acceleration and slip values for each wheel. These values are used to determine when antilock control is required.

The EBTCM/EBCM will only set one wheel speed sensor fault code at a time, even if multiple faults exist. Detection is prioritized accordingly: LF, RR, LR, RF Always check for additional stored codes after making repairs.

TEST CONDITION(S)
1. Tested continuously.

FAILURE CONDITION(S)
Continuity
1. While standing: Open circuit is seen while the vehicle is standing still with the ignition "ON."

ACTION TAKEN
1. Code set.
2. ABS/TCS switched "OFF."
3. "ANTILOCK" indicator "ON."
4. "TRACTION DISABLED" message displayed (vehicles with TCS).

Code 23 is set if there is a short to voltage or ground in CKT 872 or 883, or faulty speed sensor. The testing for this fault occurs with the ignition "ON" and the vehicle at rest.

NOTICE: A Code 21 may set if CKT 872 or 833 lose continuity and the WSS signal is lost while driving. A Code 23 should accompany this code on the subsequent ignition cycle. If both Code 21 and Code 23 are set concurrently, diagnose Code 23 first.

TEST DESCRIPTION
Test numbers refer to circled numbers on the diagnostic chart.
1. Checks for proper resistance in the sensor itself.
2. Checks for a short to battery in either of the speed sensor circuit wires. There should be 5V on CKT 872. If there is, CKT 872 has no hard opens or shorts. The condition may be intermittent.
3. Checks for an open in both the speed sensor circuit wires.
4. Manipulates wiring and connectors, trying to induce an intermittent fault not currently present.
5. This test checks if the code resets on key-up. If so, since Tests 1-4 have validated that the circuitry and components are good, the Wheel Bearing/Speed Sensor assembly may be causing the fault.
6. Checks if the Code 21 sets during a road test.
7. Code 23 sets when the vehicle is at rest: Code 21 sets with a problem in the speed sensor circuitry with the vehicle in motion. If problems are still present, Code 21 would set during the road test, not a 23. If Code 21 sets at this point, Code 21 diagnostics should be used.
8. The wheel speed sensor may be causing an intermittent fault. If Code 23 resets after sensor replacement, the EBTCM/EBCM must be concluding there is a problem present in the speed sensor circuit when there is not.

DIAGNOSTIC AIDS
Be sure the speed sensor wiring is properly routed and retained. This will help prevent false signals due to electrical noise being picked up by the wiring.

It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the fault.