DTC C1935: Ignition Switch Circuit

DTC detecting condition: 

A fault is detected after a predetermined period of time, if the hardware IGN signal and CAN IGN signal were compared and did not match.

Trouble symptom: 

Electronic parking brake warning light illuminates.

Wiring diagram: 

Vehicle dynamics control system. Refer to WIRING SYSTEM>VEHICLE DYNAMICS CONTROL SYSTEM>WIRING DIAGRAM>WITH EYESIGHT .

Courtesy of SUBARU OF AMERICA, INC.

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK VDC Control Module & H/U INPUT VOLTAGE. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the VDC Control Module & H/U.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between VDC Control Module & H/U connector and chassis ground.

      Connector & terminal 

      (B310) No. 35 (+) - Chassis ground (-):

   Is the voltage 10 - 15 V?

   Yes:  Go to  2.

   No:  Repair or replace the open circuit in the power supply circuit including the fuse.

2. CHECK VDC Control Module & H/U GROUND CIRCUIT (CHECK FOR OPEN CIRCUIT). 
   1. Turn the ignition switch to OFF.
   2. Measure the resistance between VDC Control Module & H/U connector and chassis ground.

      Connector & terminal 

      (B310) No. 14 - Chassis ground:

   Is the resistance less than 10 Ω?

   Yes:  Go to  3.

   No:  Repair the VDC Control Module & H/U ground circuit.

3. CHECK INPUT VOLTAGE OF BODY INTEGRATED UNIT. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from body integrated unit.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between body integrated unit connector and chassis ground.

      Connector & terminal 

      (B281) No. 3 (+) - Chassis ground (-):

   Is the voltage 10 - 15 V?

   Yes:  Go to  4.

   No:  Repair the power supply circuit of the body integrated unit.

4. CHECK LAN SYSTEM. 

   Check the DTC in LAN system. Refer to LAN SYSTEM (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

   Is DTC for LAN system displayed?

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

   No:  Go to  5.

5. CHECK POOR CONTACT OF CONNECTORS. 

   Is there poor contact of power supply circuit, ground circuit and VDC Control Module & H/U connector?

   Yes:  Repair the connector.

   No:  Go to  6.

6. CHECK VDC Control Module & H/U. 
   1. Connect all connectors.
   2. Perform the Clear Memory Mode. Refer to VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)>CLEAR MEMORY MODE .
   3. Perform the Inspection Mode. Refer to VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)>INSPECTION MODE .
   4. Read the DTC. Refer to VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)>READ DIAGNOSTIC TROUBLE CODE (DTC) .

   Is the same DTC displayed?

   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:  Go to  7.

7. CHECK DETECTION OF OTHER DTCS FOR VDC. 

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

   Is any other DTC displayed?

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

   No:  Currently, it is normal. There may have been a temporary poor contact in the harness and connector or a temporary noise interference.