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. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

   Was the basic diagnostic procedure performed up to step 7?

   Yes:  Go to  2.

   No:  Perform the basic diagnostic procedure. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE .

2. CHECK DTC (OTHER THAN U-CODE)  .

   Check the displayed DTC.

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

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

   No:  Go to  3.

3. CHECK DTC (CURRENT CODE)  .

   Check the displayed DTC.

   Is DTC U0127 displayed? (Current code)

   Yes:  Go to  4.

   No:  Go to  6.

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

   Is DTC U0127 displayed? (Current code)

   Yes:  Go to  5.

   No:  Go to  6.

5. CHECK DTC  .

   Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   DTC Check

   Is DTC U0127 detected in several modules? (Current code)

   Yes:  Replace the TPMS & keyless entry control module or keyless entry control module. Ref. to SECURITY AND LOCKS>KEYLESS ENTRY CONTROL MODULE .

   No:  Replace the module that the DTC has been detected.

6. CHECK HARNESS  .
   1. Shake the harness, and check for poor contact.
   2. Using the Subaru Select Monitor, read all DTCs. Ref. to LAN SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC U0127 displayed? (Current code)

   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.