Diagnostic Procedure

WARNING: This page is about a different car, the 2013 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK POOR CONTACT OF CONNECTOR. Check if there is poor contact between VDCCM&H/U and ABS wheel speed sensor.	Is there poor contact?	Repair the connector.	Go to step 2 .
2 CHECK HARNESS CONNECTOR BETWEEN VDCCM&H/U AND ABS WHEEL SPEED SENSOR. Disconnect the connector (B310) from the VDCCM&H/U. Disconnect the connector from ABS wheel speed sensor. Measure the resistance between VDCCM&H/U connector and ABS wheel speed sensor connector. Connector & terminal DTC C0021 (B310) No. 6 - (B6) No. 1: (B310) No. 5 - (B6) No. 2: DTC C0023 (B310) No. 1 - (B15) No. 1: (B310) No. 26 - (B15) No. 2: DTC C0025 (B310) No. 4 - (R72) No. 1: (B310) No. 3 - (R72) No. 2: DTC C0027 (B310) No. 27 - (R73) No. 1: (B310) No. 2 - (R73) No. 2:	Is the resistance less than 1 Ω?	Go to step 3 .	Repair the harness connector between VDCCM&H/U and ABS wheel speed sensor.
3 CHECK GROUND SHORT OF HARNESS. Measure the resistance between VDCCM&H/U connector and chassis ground. Connector & terminal DTC C0021 (B310) No. 6 - Chassis ground: DTC C0023 (B310) No. 1 - Chassis ground: DTC C0025 (B310) No. 4 - Chassis ground: DTC C0027 (B310) No. 27 - Chassis ground:	Is the resistance 1 MΩ or more?	Go to step 4 .	Repair the harness connector between VDCCM&H/U and ABS wheel speed sensor.
4 CHECK ABS WHEEL SPEED SENSOR POWER SUPPLY CIRCUIT. Connect the VDCCM&H/U connector. Turn the ignition switch to ON. Measure the voltage between ABS wheel speed sensor connector and chassis ground. Connector & terminal DTC C0021 (B6) No. 2 (+) - Chassis ground (-): DTC C0023 (B15) No. 2 (+) - Chassis ground (-): DTC C0025 (R72) No. 2 (+) - Chassis ground (-): DTC C0027 (R73) No. 2 (+) - Chassis ground (-):	Is the voltage 5 - 16 V?	Go to step 6 .	Go to step 5 .
5 CHECK VDCCM&H/U POWER SUPPLY CIRCUIT. Turn the ignition switch to OFF. Disconnect the VDCCM&H/U connector. Turn the ignition switch to ON. Measure the voltage between VDCCM&H/U connector terminals. Connector & terminal (B310) No. 28 (+) - (B310) No. 25 (-):	Is the voltage 10 - 15 V?	Go to step 6 .	Check the generator, battery and VDCCM&H/U power supply circuit.
6 CHECK ABS WHEEL SPEED SENSOR SIGNAL. Install the ABS wheel speed sensor. Prepare an oscilloscope. Check the ABS wheel speed sensor. < Refer to FRONT ABS WHEEL SPEED SENSOR , INSPECTION, Front ABS Wheel Speed Sensor. >	Is the pattern the same waveform as shown in the figure?	Go to step 7 .	Replace the ABS wheel speed sensor. < Refer to FRONT ABS WHEEL SPEED SENSOR . >
7 CHECK VDCCM&H/U. Connect all connectors. Clear the memory. < Refer to CLEAR MEMORY MODE . > Perform the Inspection Mode. < Refer to INSPECTION MODE . > Read the DTC.	Is the same DTC displayed?	Replace the VDCCM only. < Refer to REPLACEMENT , VDC Control Module and Hydraulic Control Unit (VDCCM&H/U). >	Go to step 8 .
8 CHECK OTHER DTC DETECTION.	Is any other DTC displayed?	Perform the diagnosis according to DTC. < Refer to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	It results from a temporary noise interference.