DTC U145B: Invalid Data Received From Restraints Control Module Local Bus

Diagnosis start condition  :

When ignition switch is ON.

DTC detecting condition  :

• Defective airbag.
• Defective DCM.

Trouble symptom  :

• Impossible to send AACN data.
• RED LED illuminates.

Failure detection pattern  :

• Detection by a single system (Primary Failure)

Warning light/indicator light  :

• Both ON -
• GREEN LED ON -
• GREEN LED blinks -
• RED LED ON O
• RED LED blinks -
• Both OFF -

Wiring diagram  :

CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Telematics] using the Subaru Select Monitor. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC U145B displayed? (Current code)

   Yes  : GO TO  2.

   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.
2. REMOVE OR INSTALL VEHICLE BATTERY TERMINAL  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the ground terminal from battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   3. After five seconds, connect the ground terminal to battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   4. Turn the ignition switch to ON.
   5. Read the DTC of [Telematics] using the Subaru Select Monitor. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC U145B displayed? (Current code)

   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.
3. CHECK DCM (INTERNAL RESISTANCE)  .
   1. Turn the ignition switch to OFF, and wait for 60 seconds or more after disconnecting the ground terminal from the battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
   2. Disconnect the airbag control module connector.
   3. Connect the connector (1BF) in the test harness BF to the airbag control module connector.
   4. Using a tester, measure the resistance between connectors in test harness BF. (Measure the internal resistance of DCM from the test harness connector.)
      CAUTION: To measure the voltage and resistance of airbag system component, be sure to use the specified test harness. Ref. to AIRBAG (DIAGNOSTICS)>GENERAL DESCRIPTION .

      Connector & terminal 

      (8BF) No. 1 - (8BF) No. 2: (internal resistance of DCM) 

   Is the resistance 114 - 126 Ω?

   Yes  : GO TO  4.

   No  : Replace the DCM. Ref. to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .

4. CHECK AIRBAG CONTROL MODULE (INTERNAL RESISTANCE)  .
   1. Disconnect the DCM connector (i105).
   2. Connect the airbag control module connector.
   3. Using a tester, measure the resistance between DCM connectors. (Measure the internal resistance of airbag control module from DCM connectors)

      Connector & terminal 

      (i105) No. 6 - (i105) No. 16: (internal resistance of airbag control module) 

   Is the resistance 114 - 126 Ω?

   Yes  : GO TO  5.

   No  : Replace the airbag control module. Ref. to AIRBAG SYSTEM>AIRBAG CONTROL MODULE .

5. CHECK DCM  .
   1. Restore the vehicle to its original state.
   2. Turn the ignition switch to ON.
   3. Using the Subaru Select Monitor, perform the clear memory of [Telematics]. Ref. to COMMON (DIAGNOSTICS)>CLEAR MEMORY .
   4. Turn the ignition switch to OFF.
   5. Turn the ignition switch to ON.
   6. Wait for 1 minute.
   7. Read the DTC of [Telematics] using the Subaru Select Monitor. Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC U145B displayed? (Current code)

   Yes  : Replace the DCM. Ref. to ENTERTAINMENT & MONITORING>DATA COMMUNICATION MODULE .

   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.