DTC U0127: Lost Communication With Tire Pressure Monitor Control Module And/Or Keyless Entry Control Module

DTC detecting condition: 

Data does not arrive from TPMS & keyless entry control module or keyless entry control module.

Trouble symptom: 

Keyless entry does not operate normally.

1. CHECK CAN COMMUNICATION HARNESS. 

   Perform the basic diagnostic procedure to check for fault in CAN communication harness. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE .

   Was the basic diagnostic procedure performed up to step 7?

   Yes:  Go to  2.

   No:  Perform the basic diagnostic procedure. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>BASIC DIAGNOSTIC PROCEDURE .

2. CHECK DTC (OTHER THAN U-CODE). 

   Check the displayed DTC.

   Is DTC other than U*** displayed? (Current malfunction)

   Yes:  Perform the diagnosis for DTCs other than the displayed U-code.

   No:  Go to  3.

3. CHECK DTC (CURRENT MALFUNCTION). 

   Check the displayed DTC.

   Is DTC U0127 displayed? (Current malfunction)

   Yes:  Go to  4.

   No:  Go to  6.

4. CHECK DTC. 
   1. Check CAN communication circuit. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>CAN COMMUNICATION CIRCUIT CHECK .
   2. Using the Subaru Select Monitor, read all DTCs. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

      Is DTC U0127 displayed? (Current malfunction)

   Yes:  Go to  5.

   No:  Go to  6.

5. CHECK DTC. 

   Using the Subaru Select Monitor, read all DTCs. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

   Is U0127 detected in several modules? (Current malfunction)

   Yes:  Replace the TPMS & keyless entry control module or keyless entry control module. Refer to SECURITY AND LOCKS>KEYLESS ENTRY CONTROL MODULE . Refer to WHEEL AND TIRE SYSTEM>TIRE PRESSURE MONITORING SYSTEM .

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

6. CHECK HARNESS. 
   1. Shake the harness and check for poor contact.
   2. Read the DTC using Subaru Select Monitor. Refer to LAN SYSTEM (DIAGNOSTICS) (EXCEPT FOR HEV)>DIAGNOSTIC TROUBLE CODE (DTC)>OPERATION .

      Is DTC U0127 displayed? (Current malfunction)

   Yes:  Repair the poor contact of harness or replace the harness.

   No:  Go to  7.

7. CHECK CONNECTOR. 

   Check the connector used for high speed CAN for poor contact.

   Is there poor contact of connector?

   Yes:  Repair the connector that has poor contact, or replace harness.

   No:  It is possible that temporary poor communication occurs. Delete the DTC.