A024

Diagnostic Chart:

Wiring Diagram:

Circuit Description:
As a toothed ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce a sinusoidal (AC) voltage signal whose frequency is proportional to wheel speed. The magnitude of this signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring, often referred to as the air gap.

Failure Condition:
DTC A024 can be set when the vehicle is not in an ABS stop. If the rear wheel speed =0 and the vehicle's reference speed is greater than 8 km/h (5 mph), a malfunction exists.

Action Taken:
A malfunction DTC is stored, ABS is disabled and the "ABS INOP" lamp is turned "ON."

Test Description:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines if DTC A035 is present.
2. This test verifies whether the malfunction is currently present.
3. This step is designed to identify a wheel speed sensor or circuitry that is damaged and visibly apparent.
4. This test checks to see that the wheel speed sensor is within proper resistance values.
5. This step verifies that the wheel speed sensor can generate an appropriate output signal.
6. This test checks for proper output voltage from the EBCM.
7. This checks for an open in the wheel signal low circuit.
8. This step insures that DTC A()24 was not set due to a poor connection between the 32-way EBCM connector and the EBCM.
9. This test insures that wheel speed sensor circuitry is not internally shorted.
10. This checks for an open in the wheel signal high circuit.

Diagnostic Aids:
An "Intermittent" malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.

The frequency of the malfunction can be checked by using the enhanced diagnostic function of the Tech 1, as described in "Tech 1 Diagnostics."