Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc u0073 control module communication bus off

Subaru Legacy BN/BS (2015-2019) Service Manual / Hvac system (diagnostics) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc u0073 control module communication bus off

DTC DETECTING CONDITION:

• Data to be received via CAN communication do not arrive.

• A/C cooperation control does not operate.

TROUBLE SYMPTOM:

A/C does not operate fully automatically.

STEP	CHECK	YES	NO
1.CHECK LAN SYSTEM. Check LAN system using the Subaru Select Monitor. Basic Diagnostic Procedure	Is there any fault-	Perform the diagnosis according to the inspection for LAN system.	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0073 CONTROL MODULE COMMUNICATION BUS OFF
2.CHECK A/C CM. 1) Replace with a normally operating A/C CM. 2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)	Is U0073 detected-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC U0073 CONTROL MODULE COMMUNICATION BUS OFF	Replace the A/C CM. Control Unit > REMOVAL
3.CHECK CAN COMMUNICATION CIRCUIT. Check the CAN communication circuit. CAN Communication Circuit Check > LIST	Is the CAN communication circuit normal-	It is possible that temporary poor communication occurs. Clear the memory. Clear Memory Mode	Repair or replace the CAN communication circuit.

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Other materials:

Inspection
1. Remove the bulkhead harness connector from TCM. Transmission Control Module (TCM) > REMOVAL2. Set the ST between the TCM and bulkhead harness.ST 18460AA040CHECK BOARD3. Set the probe of oscilloscope to the check board connector.Terminals:No. 14 (+) — No. 42 (−)(A)+ probe(B)− pro ...