DTC U0230: Lost Communication With Power Rear Gate Control Module

DTC detecting condition:

No data is received from the power rear gate Control Module.

Trouble symptom:

The power rear gate does not operate normally.

Wiring diagram:

Power rear gate system Ref. to WIRING SYSTEM>Power Rear Gate System>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CHECK DTC .
Read the DTC of body integrated unit using Subaru Select Monitor. Ref. to BODY CONTROL(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .

Is DTC U0230 displayed? (Current malfunction)

Yes: Go to 2.

No: It is possible that temporary poor contact occurs. Perform the clear memory operation. Ref. to BODY CONTROL(DIAGNOSTICS)>Clear memory .
CHECK DTC .
1. Turn the ignition switch to OFF.
2. Disconnect the power rear gate Control Module and body integrated unit connectors.
3. Connect the disconnected connectors.
4. Using the Subaru Select Monitor, read DTC of CAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC U0230 displayed? (Current malfunction)

Yes: Go to 3.

No: Even if DTC is displayed, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the power rear gate Control Module and body integrated unit connectors.
3. Using the tester, measure the resistance between terminals.
  Connector & terminal
  
  (i171) No. 16 - (R423) No. 1:
  
  (R422) No. 14 - Chassis ground:
  
  (R423) No. 8 - Chassis ground:
Is the resistance less than 10 Ω

Yes: Go to 4.

No: Repair the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
1. Disconnect the power seat Control Module connector. (With power seat memory)
2. Using the tester, measure the resistance between terminals.
  Connector & terminal
  
  (R423) No. 1 - Chassis ground:
Is the resistance 10 kΩ or more?

Yes: Go to 5.

No: Repair the shorted portion of harness.
CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY) .
1. Turn the ignition switch to ON.
2. Using the tester, measure the voltage between terminals.
  Connector & terminal
  
  (R423) No. 1 (+) - Chassis ground (-):
Is the voltage less than 1 V?

Yes: Go to 6.

No: Repair the shorted portion of harness.
CHECK HARNESS (POWER SUPPLY CIRCUIT) .
1. Turn the ignition switch to ON.
2. Using the tester, measure the voltage between terminals.
  Connector & terminal
  
  (R422) No. 1 (+) - Chassis ground (-):
  
  (R422) No. 10 (+) - Chassis ground (-):
  
  (R422) No. 8 (+) - Chassis ground (-):
Is the voltage 9 V or more when the IG switch is ON?

Yes: Go to 7.

No: Repair the open circuit of harness.
CHECK CONTROL MODULE .
1. Turn the ignition switch to OFF.
2. Replace the power rear gate Control Module with a properly functioning part. Ref. to POWER REAR GATE SYSTEM>POWER REAR GATE CONTROL MODULE .
3. Read the DTC of body integrated unit using Subaru Select Monitor. Ref. to BODY CONTROL(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .
Is DTC U0230 displayed? (Current malfunction)

Yes: Replace the body integrated unit. Ref. to SECURITY AND LOCKS>BODY INTEGRATED UNIT .

No: For models without power seat memory, malfunction occurred in the power rear gate Control Module. For models with power seat memory, Go to 8.
CHECK CONTROL MODULE .
1. Connect the power seat Control Module connector.
2. Read the DTC of body integrated unit using Subaru Select Monitor. Ref. to BODY CONTROL(DIAGNOSTICS)>Diagnostic Trouble Code (DTC) .
Is DTC U0230 displayed? (Current malfunction)

Yes: Replace the power seat Control Module. Ref. to SEATS>POWER SEAT SYSTEM .

No: Malfunction occurred in the power rear gate Control Module.