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 .

   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 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. 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)>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. Ref. to LAN SYSTEM (DIAGNOSTICS)>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. Ref. to SECURITY AND LOCKS>KEYLESS ENTRY CONTROL MODULE . Ref. to WHEEL AND TIRE SYSTEM>TIRE PRESSURE MONITORING SYSTEM .

   No  : Replace the combination meter. Ref. 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. Ref. to LAN SYSTEM (DIAGNOSTICS)>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.