Error Messages and Codes 3-17
Transfer Roller Contact Failure, Code 20
Transfer Roller Retract Failure, Code 21
The Transfer Roller did not meet the contact position, or the Transfer Roller did not 
reach the retract position.
Troubleshooting References 
Applicable Parts Wiring and Plug/Jack Map References
■ Left Door
■ Retract Home Sensor
■ Engine Control Board
Troubleshooting Procedure 
Step Actions and Questions Yes No
1
1. Enter service diagnostics and run the 
2nd BTR Motor test.
2. Does the motor operate correctly?
Go to step 2. Go to step 5.
2
1. Clean the 2nd BTR retract sensor.
2. Does the error still occur?
Go to step 3. Complete.
3
1. Use service diagnostics transmissive 
sensor test.
2. Does the sensor operate correctly?
Go to step 4. Replace the 
sensor or left 
hand door 
assembly.
4
1. Check the transfer roller transmission 
gears for damage.
2. Are the gears damaged?
Replace the left 
hand door 
assembly.
Go to step 6.
5
1. Remove the left-hand rear mid cover.
2. Inspect the left-hand cover assembly 
wiring harness for damage and ensure 
the connectors are all properly seated.
3. Is the wiring harness damaged?
Replace the left-
hand cover 
assembly.
Go to step 6.
6
1. Remove the rear cover and rear shield.
2. Reconnect power and enter service 
diagnostics.
3. Measure the voltage at the engine 
control board J533B9 while running the 
2nd BTR Motor test several times.
4. Does the voltage toggle between 
+5 VDC and 0 VDC when the test is 
running?
Replace the 
engine control 
board.
Replace the 
transfer roller 
retract sensor.