DTC B2645: Mirror P Courtesy Lamp Circuit Anomalous State

DTC detecting condition:

When the courtesy light driver circuit detects overcurrent (8 A or more).
When the courtesy light driver circuit detects overheat.
When a communication (ECM internal signal) error in the courtesy light driver circuit is detected.
Trouble symptom:

The following functions do not operate.
Door step light illumination (passenger's seat)

Wiring diagram:

Interior light system Ref. to WIRING SYSTEM>INTERIOR LIGHT SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. 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. Ref. to Door Mirror (Diagnostics)>Diagnostic Trouble Code (DTC) .
  Is DTC B2645 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 FRONT DOOR STEP LIGHT (PASSENGER'S SEAT) .
1. Turn the ignition switch to OFF.
2. Disconnect the front door step light (passenger's seat) connector (Df59).
3. Apply battery voltage between front door step light (passenger's seat) connector terminals, and check if the light illuminates.
  Connector and terminal
  
  No. 2 (+) - No. 1 (-):
  
  Does the light illuminate?
  
  Yes : Go to 3 .
  
  No : Replace the front door step light (passenger's seat). Ref. to LIGHTING SYSTEM>DOOR STEP LIGHT .
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 and terminal
  
  (Df24) No. 5 (+) - 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 front door step light (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 and terminal
  
  (Df24) No. 5 - Chassis ground:
  
  Is the resistance 1 MΩ or more?
  
  Yes : Replace the outer mirror control module (passenger's seat). Ref. to GLASS/WINDOW/MIRRORS>OUTER MIRROR CONTROL MODULE .
  
  No : Repair the short circuit to ground in harness between outer mirror control module (passenger's seat) connector and front door step light (passenger's seat) connector.