Diagnostic Procedure for Subaru Select Monitor Communication: Inspection

Communication error with auto headlight beam leveler control module

Detecting condition :

Defective harness connector
Power supply circuit malfunction
Defective auto headlight beam leveler control module
Defective CAN communication circuit
Defective Subaru Select Monitor

Trouble symptom :

Communication is impossible between auto headlight beam leveler control module and Subaru Select Monitor.

Wiring diagram :

Headlight beam leveler system Ref. to WIRING SYSTEM>HEADLIGHT BEAM LEVELER SYSTEM>WIRING DIAGRAM .
CAN communication system Ref. to WIRING SYSTEM>CAN COMMUNICATION SYSTEM>WIRING DIAGRAM .
Without SRH

Courtesy of SUBARU OF AMERICA, INC.
With SRH

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Initialization is required after replacing the auto headlight beam leveler control module . Ref. to LIGHTING SYSTEM>AUTO HEADLIGHT BEAM LEVELER SYSTEM>PROCEDURE .

CHECK FUSE .
Check the fuse. Ref. to WIRING SYSTEM>HEADLIGHT BEAM LEVELER SYSTEM>WIRING DIAGRAM .

Is the check result OK?

Yes: Go to 2.

No: Replace the fuse. If the replaced fuse has blown out immediately, repair the short circuit to ground in harness between battery and auto headlight beam leveler control module.
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the connector from the auto headlight beam leveler control module.
3. Turn the ignition switch to ON.
4. Using a tester, measure the voltage between auto headlight beam leveler control module connector and chassis ground.
  Connector & terminal
  
  Without SRH
  
  (B78) No. 1 (+) - Chassis ground (-):
  
  With SRH
  
  (B78) No. 1 (+) - Chassis ground (-):
  
  (B78) No. 3 (+) - Chassis ground (-):
Is the voltage 10 - 13 V?

Yes: Go to 3.

No: Repair the open circuit in the harness between auto headlight beam leveler control module connector and fuse.
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Using a tester, measure the resistance between the auto headlight beam leveler control module connector and chassis ground.
  Connector & terminal
  
  (B78) No. 2 - Chassis ground:
  
  Is the resistance less than 1 Ω?
Yes: Go to 4.

No: Repair the open circuit of harness between auto headlight beam leveler control module connector and chassis ground.
CHECK LAN SYSTEM .
Inspect LAN system. Ref. to LAN SYSTEM (DIAGNOSTICS)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

Is the check result OK?

Yes: Go to 5.

No: Perform the inspection according to the diagnosis for LAN system.
CHECK SUBARU SELECT MONITOR .
1. Connect the select monitor to another vehicle.
2. Check whether the communication for initializing can be executed normally.
Is communication normal?

Yes: Go to 6.

No: Repair or replace the Subaru Select Monitor.
CHECK AUTO HEADLIGHT BEAM LEVELER CONTROL MODULE .
1. Turn the ignition switch to OFF.
2. Connect the auto headlight beam leveler control module connector.
3. Turn the ignition switch to ON.
4. Communicate with [Headlight/Foglight] using the Subaru Select Monitor.
Is communication possible?

Yes: 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.

No: Replace the auto headlight beam leveler control module. Ref. to LIGHTING SYSTEM>AUTO HEADLIGHT BEAM LEVELER CONTROL MODULE .