Hill Start Assist On/Off Mode

NOTE: This diagnosis is applied only to the model without EyeSight.

Detecting condition

Defective combination meter
Defective CAN communication
Defective VDC OFF switch

Trouble symptom

Hill start assist warning light does not illuminate or go off when hill start assist function ON/OFF is changed. (Hill start assist mode does not change.)

NOTE:

When the VDC OFF switch is kept pressed, VDC OFF indicator light illuminates in yellow, then goes off in approx. 30 seconds. If the switch is released in 5 seconds after the light goes off then pressed again in 2 seconds, hill start assist warning light illuminates then mode is changed to hill start assist OFF mode.
Hill start assist warning light always illuminates to inform that the hill start assist does not operate during hill start assist OFF mode.
When pressing the VDC OFF switch for 30 seconds or more, the VDC OFF indicator light goes off and cannot operate any more. When turning the ignition switch from OFF to ON, the operation enabled status is restored.

Wiring diagram:

Vehicle dynamics control system. Refer to WIRING SYSTEM>VEHICLE DYNAMICS CONTROL SYSTEM>WIRING DIAGRAM>WITHOUT EYESIGHT .

Courtesy of SUBARU OF AMERICA, INC.

READ DTC.
Read the DTC. Refer to VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

Is DTC displayed?

Yes: Perform the diagnosis according to DTC. Refer to VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)>LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .

No: Go to 2.
CHECK HARNESS.
1. Turn the ignition switch to OFF.
2. Disconnect the connector from the VDC Control Module & H/U and VDC OFF switch.
3. Measure the resistance of harness between the VDC Control Module & H/U and VDC OFF switch connectors.
  Connector & terminal
  
  (B310) No. 20 - (i234) No. 5:
Is the resistance less than 1 Ω?

Yes: Go to 3.

No: Repair the harness between the VDC Control Module & H/U and VDC OFF switch connectors.
CHECK GROUND SHORT OF HARNESS.
Measure the resistance between VDC Control Module & H/U connector and chassis ground.

Connector & terminal

(B310) No. 20 - Chassis ground:

Is the resistance 1 Ω or more?

Yes: Go to 4.

No: Repair the harness between the VDC Control Module & H/U and VDC OFF switch connectors.
CHECK HARNESS.
Measure the resistance of harness between VDC OFF switch connector and chassis ground.

Connector & terminal

(i234) No. 6 - Chassis ground:

Is the resistance less than 10 Ω?

Yes: Go to 5.

No: Repair the harness between the VDC OFF switch connector and chassis ground.
CHECK VDC OFF SWITCH.
Check the VDC OFF switch. Refer to VEHICLE DYNAMICS CONTROL (VDC)>VDC OFF SWITCH>INSPECTION .

Is the check result OK?

Yes: Go to 6.

No: Replace the VDC OFF switch. Refer to VEHICLE DYNAMICS CONTROL (VDC)>VDC OFF SWITCH .
CHECK LAN SYSTEM.
Perform the diagnosis for LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

Is there any fault in LAN system?

Yes: Perform the diagnosis according to DTC for LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .

No: Go to 7.
CHECK COMBINATION METER.
Check the combination meter. Refer to INSTRUMENTATION/DRIVER INFO>COMBINATION METER SYSTEM>INSPECTION .

Is the check result OK?

Yes: Replace the VDC Control Module & H/U. Refer to VEHICLE DYNAMICS CONTROL (VDC)>VDC CONTROL MODULE AND HYDRAULIC CONTROL UNIT (VDC Control Module & H/U) .

No: Replace the combination meter. Refer to INSTRUMENTATION/DRIVER INFO>COMBINATION METER .