DTC B1390: Power Tailgate Closer Function Error

WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

With the tailgate closed, pull the tailgate outer handle and wait for 10 seconds.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Clear the DTCs with the HDS.
Listen for the sound of the latch releasing.
Is there sound?

YES -Go to step 5.

NO -Go to step 7.
Check for DTCs with the HDS.
Is DTC B1390 indicated?

YES -Go to step 6.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections between the power tailgate control unit and the closer motor.
Check for DTCs with the HDS.
Are DTCs B1380, B1381, B1382, B1383, and/or B1384 also indicated?

YES -Go to the indicated DTCS TROUBLESHOOTING .

NO -Replace the power tailgate control unit and recheck the system.
Turn the ignition switch to LOCK (0).
Open the tailgate.
Disconnect the 2P connector from the power tailgate closer motor.
Disconnect power tailgate control unit connector B (20P).
Check for continuity between power tailgate control unit connector B (20P) terminals No. 1 and No. 2 and power tailgate closer motor 2P connector terminals No. 1 and No. 2 respectively.

Fig 1: Checking Continuity Between Connector B (20P) Terminals And 2P Connector Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 12.

NO -Repair an open in the wire.
Measure the voltage between power tailgate control unit connector B (20P) terminal No. 12 and body ground.

Fig 2: Measuring Voltage Between Connector B (20P) Terminal No. 12 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 13.

NO -Check the No. 6 (20 A) fuse in the rear fuse/relay box. If the fuse is OK, check for an open in the wire between the rear fuse/relay box and power tailgate control unit.
Disconnect power tailgate control unit connector A (5P).
Check for continuity between power tailgate control unit connector A (5P) terminal No. 4 and body ground.

Fig 3: Checking Continuity Between Connector (5P) Terminal No. 4 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 15.

NO -Repair an open in the wire or poor ground (G701).
Turn the tailgate lock latch to the fully-closed position using a screwdriver.
Reconnect the power tailgate closer motor 2P connector.
Connect battery power to power tailgate control unit connector B (20P) terminal No. 2 (or No. 1) and ground terminal No. 1 (or No. 2) momentarily.

Fig 4: Identifying Connector B (20P) Terminals Connection With Battery
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Does the motor run smoothly?

YES -Replace the power tailgate control unit.

NO -Go to step 18.
Check for continuity between body ground and power tailgate control unit connector B (20P) terminals No. 1 and No. 2 individually.

Fig 5: Checking Continuity Between Body Ground And Connector B (20P) Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 19.

NO -Go to step 21.
Disconnect the 2P connector from the power tailgate closer motor.
Check for continuity between body ground and power tailgate control unit connector B (20P) terminals No. 1 and No. 2 individually.

Fig 6: Checking Continuity Between Body Ground And Connector B (20P) Terminals No. 1 And No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Replace the power tailgate closer unit.
Check for continuity between power tailgate control unit connector B (20P) terminal No. 9 and body ground.

Fig 7: Checking Continuity Between Connector B (20P) Terminal No. 9 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Check for No. 6 (20 A) fuse in the rear fuse/relay box. If the fuse is OK, check for an open in the wire between the rear fuse/relay box and power tailgate control unit.