A031

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.

This DTC is designed to detect two open wheel speed sensors in any combination. This DTC exists due to a condition that may exist that does not allow the driver to be informed by the ABS indicator lamp of non-functioning ABS. If one wheel speed sensor is open, the driver is informed. If a second fails, the driver is no longer informed without this DTC and ABS is not available. By requiring the two operating wheels to be within 7 mph, a false DTC is prevented during spin-ups while still allowing for detection when the stowaway spare tire is used.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test verifies whether the malfunction is currently present.
2. This step is designed to identify a wheel speed sensor or circuitry that is damaged and visibly apparent.
3. This step identifies if the cause of the malfunction is common to the rear wheel sensor circuitry.
4. This test checks to see if connectors at pass thru are connected properly.
5. This test checks to see that the wheel speed sensor is within proper resistance values.
6. This step checks for an open in the wheel speed sensor circuitry of one side of the sensor.
7. This step checks for an open on the other side of the sensor in question.
8. This insures that the circuitry is not shorted to voltage.

DIAGNOSTIC AIDS
A false DTC A031 may be set as a result of vehicle operation while on a hoist or a lifted condition or stuck in mud or snow, when the vehicle is in gear.

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 the "Tech 1 Diagnostics".