DTC 23

Codes 23, 27 & 37: Wheel Speed Sensor Circuit Continuity Fault (Part 1 Of 2).:

Codes 23, 27 & 37: Wheel Speed Sensor Circuit Continuity Fault (Part 2 Of 2).:

Front Wheel Speed Sensor Circuit Fault:

CIRCUIT DESCRIPTION
The toothed wheel generates a voltage pulse as it moves past the sensor; each tooth-gap-tooth series on the wheel generates a pulse. The frequency of these pulses is used by the EBCM to determine wheel speed. The amplitude of the voltage generated in each pulse depends on the air gap between the sensor and the toothed wheel, and on wheel speed.

DTC WILL SET WHEN
- There is a short to voltage or an open in the affected circuit.
- There is a malfunctioning speed sensor.

The test for this malfunction occurs any time with the ignition in the "RUN" position.

ACTION TAKEN
The "ABS" lamp will be "ON." ABS is disabled.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Check for proper resistance in the sensor itself.
2. Checks for a short to voltage in either of the speed sensor circuit wires.
3. Checks for an open in both the speed sensor circuit wires.
4. Manipulates wiring and connectors, trying to induce an intermittent malfunction not currently present.
5. This test checks if the DTC resets.
6. Checks if DTC (21 RF),(25 LF) or (35 R) sets during a road test.
7. If the circuit malfunctions DTC sets at this point, diagnostics for circuit malfunctions should be used.
8. The wheel speed sensor may be causing an intermittent malfunction. If DTC resets after sensor replacement, the EBCM must be concluding there is a malfunction 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 malfunction.