DTC B2621: Mirror SW Anomalous State

DTC detecting condition: 

When any of operation statuses (up, down, left or right) of R side mirror surface switch continues for 20 seconds.

or

When any of operation statuses (up, down, left or right) of L side mirror surface switch continues for 20 seconds.

Trouble symptom: 

The following functions do not operate.

• Mirror surface angle manual adjustment function

Wiring diagram: 

Remote control mirror system Ref. to WIRING SYSTEM>REMOTE CONTROL MIRROR SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK DTC  .
   1. Turn the ignition switch to ON, and wait for 20 seconds or more.
   2. Read the DTC of [Door Mirror (Driver)] using the Subaru Select Monitor. Ref. to Door Mirror (Diagnostics)>Diagnostic Trouble Code (DTC) .

      Is DTC B2621 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.
2. CHECK REMOTE CONTROL MIRROR SWITCH  .
   1. Turn the ignition switch to OFF.
   2. Check remote control mirror switch unit. Ref. to GLASS/WINDOW/MIRRORS>REMOTE CONTROL MIRROR SWITCH .

      Is the remote control mirror switch OK?

      Yes  : Go to  3 .

      No  : Replace the remote control mirror switch. Ref. to GLASS/WINDOW/MIRRORS>REMOTE CONTROL MIRROR SWITCH .

3. CHECK HARNESS (SHORT CIRCUIT TO POWER SUPPLY)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the outer mirror control module (driver's seat) connector.
   3. Disconnect the remote control mirror switch connector.
   4. Turn the ignition switch to ON.
   5. Using a tester, measure the voltage between outer mirror control module (driver's seat) connector and chassis ground.

      Connector and terminal 

      (Df21) No. 8 (+) - Chassis ground (-):

      (Df21) No. 9 (+) - Chassis ground (-):

      (Df21) No. 10 (+) - Chassis ground (-):

      (Df21) No. 11 (+) - Chassis ground (-):

      (Df21) No. 12 (+) - 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 (driver's seat) connector and remote control mirror switch connector.

4. CHECK HARNESS (GROUND SHORT CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Using a tester, measure the resistance between outer mirror control module (driver's seat) connector and chassis ground.

      Connector and terminal 

      (Df21) No. 8 - Chassis ground:

      (Df21) No. 9 - Chassis ground:

      (Df21) No. 10 - Chassis ground:

      (Df21) No. 11 - Chassis ground:

      (Df21) No. 12 - Chassis ground:

      Is the resistance 1 MΩ or more?

      Yes  : Go to  5 .

      No  : Repair the short circuit to ground in harness between outer mirror control module (driver's seat) connector and remote control mirror switch connector.

5. CHECK OUTER MIRROR CONTROL MODULE (DRIVER'S SEAT)  .
   1. Turn the ignition switch to OFF.
   2. Connect all connectors.
   3. Turn the ignition switch to ON.
   4. Using the Subaru Select Monitor, check the following items in the [Data monitor] of [Door Mirror (Driver)]. Ref. to Door Mirror (Diagnostics)>Data Monitor .
      • Mirror SW Input Status

      Does the input value change corresponding to the switch operation?

      Yes  : 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.

      No  : Replace the outer mirror control module (driver's seat). Ref. to GLASS/WINDOW/MIRRORS>OUTER MIRROR CONTROL MODULE .