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.

Wiring diagram:

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

Courtesy of SUBARU OF AMERICA, INC.

CAUTION:

After replacing DCM, it will be required to confirm the green LED blinking, turn IGN ON while holding the SOS button during IGN OFF, and then release the SOS button to enter eCall ON.
Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to TELEMATICS SYSTEM (DIAGNOSTICS)>GENERAL DESCRIPTION>CAUTION .

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.
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.
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 .

Terminals

(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 .
CHECK AIRBAG CONTROL MODULE (INTERNAL RESISTANCE) .
1. Disconnect the DCM connector.
2. Connect the airbag Control Module connector.
3. Measure the resistance between DCM connectors. (Measure the internal resistance of airbag Control Module from DCM connectors)
Terminals

(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 .
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.