Subaru Crosstrek Service Manual: Dtc c0042 power supply voltage failure

DTC detecting condition:

Improper VDCCM&H/U power supply voltage

Trouble symptom:

• ABS does not operate.

• EBD may not operate.

• VDC does not operate.

• EyeSight does not operate.

Warning lights go off if voltage returns.

1.CHECK GENERATOR.

1) Start the engine.

2) Run the engine at idle after warming up.

3) Measure the voltage between generator terminal B and chassis ground.

Terminals

Generator terminal B (+) — Chassis ground (−):

Is the voltage 10 — 15 V?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 2.

Repair the generator.

2.CHECK BATTERY TERMINAL.

Turn the ignition switch to OFF.

Are the positive and negative battery terminals clamped tightly?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 3.

Install the battery terminal correctly.

3.CHECK VDCCM&H/U INPUT VOLTAGE.

1) Disconnect the connector from the VDCCM&H/U.

2) Run the engine at idle.

3) Operate devices such as headlights, air conditioner, defogger, etc. which produce an electrical load.

4) Measure the voltage between VDCCM&H/U connector and chassis ground.

Connector & terminal

(B310) No. 1 (+) — Chassis ground (−):

(B310) No. 14 (+) — Chassis ground (−):

(B310) No. 20 (+) — Chassis ground (−):

Is the voltage 10 — 15 V?

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 4.

Repair the power supply circuit.

4.CHECK VDCCM&H/U GROUND CIRCUIT (CHECK FOR OPEN CIRCUIT).

1) Turn the ignition switch to OFF.

2) Measure the resistance between VDCCM&H/U connector and chassis ground.

Connector & terminal

(B310) No. 26 — Chassis ground:

Is the resistance less than 10 ??

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 5.

Repair the VDCCM&H/U ground harness.

5.CHECK POOR CONTACT OF CONNECTORS.

Is there poor contact of connector between generator, battery and VDCCM&H/U?

Repair the connector.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 6.

6.CHECK VDCCM&H/U.

1) Connect all connectors.

2) Perform the Clear Memory Mode. Clear Memory Mode">

3) Perform the Inspection Mode. Inspection Mode">

4) Read the DTC. Read Diagnostic Trouble Code (DTC)">

Is the same DTC displayed?

Replace the VDCCM&H/U. VDC Control Module and Hydraulic Control Unit (VDCCM&H/U)">

Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0042 POWER SUPPLY VOLTAGE FAILURE">Go to Step 7.

7.CHECK DETECTION OF OTHER DTCS FOR VDC.

Read Diagnostic Trouble Code (DTC)">

Is any other DTC displayed?

Perform the diagnosis according to DTC. List of Diagnostic Trouble Code (DTC)">

Currently, it is normal. There may have been a temporary poor contact in the harness and connector or a temporary noise interference.

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