DTC B2643: Mirror P Heater Circuit Anomalous State

DTC detecting condition:

When the heater driver circuit detects Over current (8 A or more).
When the heater driver circuit detects overheat.
When a communication (ECM internal signal) error in the heater driver circuit is detected.

Trouble symptom:

The following functions do not operate.

Mirror heater operation (passenger's seat)

Wiring diagram:

Mirror heater system Refer to WIRING SYSTEM>MIRROR HEATER SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Refer to DOOR MIRROR (DIAGNOSTICS)>GENERAL DESCRIPTION>INSPECTION .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Read the DTC of [Door Mirror (Passenger)] using the Subaru Select Monitor. Refer to DOOR MIRROR (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .
Is DTC B2643 displayed? (Current malfunction)

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 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 OUTER MIRROR ASSEMBLY (PASSENGER'S SEAT) .
1. Turn the ignition switch to OFF.
2. Disconnect the outer mirror assembly (passenger's seat) connector (Df55).
3. Apply battery voltage between outer mirror assembly (passenger's seat) connector terminals, and operate the mirror heater.
  Connector & terminal
  
  No. 13 (+) - No. 14 (-):
4. Using a tester in the state of step 3, measure the current between outer mirror assembly (passenger's seat) connector terminals.
  Connector & terminal
  
  No. 13 (+) - No. 14 (-):
Is the current 2.6 A or less?

Yes : Go to 3.

No : Replace the outer mirror assembly (passenger's seat). Refer to GLASS/WINDOWS/MIRRORS>OUTER MIRROR ASSEMBLY .
CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY) .
1. Disconnect the outer mirror Control Module (passenger's seat) connector.
2. Turn the ignition switch to ON.
3. Using a tester, measure the voltage between outer mirror Control Module (passenger's seat) connector and chassis ground.
  Connector & terminal
  
  (Df24) No. 14 (+) - Chassis ground (-):
Is the voltage less than 1 V?

Yes : Go to 4.

No : Repair the short circuit to power supply in harness between outer mirror Control Module (passenger's seat) connector and outer mirror assembly (passenger's seat) connector.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Using a tester, measure the resistance between outer mirror Control Module (passenger's seat) connector and chassis ground.
  Connector & terminal
  
  (Df24) No. 14 - Chassis ground:
Is the resistance 1 MΩ or more?

Yes : Replace the outer mirror Control Module (passenger's seat). Refer to GLASS/WINDOWS/MIRRORS>OUTER MIRROR Control Module .

No : Repair the short circuit to ground in harness between outer mirror Control Module (passenger's seat) connector and outer mirror assembly (passenger's seat) connector.