DTC B1388: Power Tailgate Motor Circuit Malfunction

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.

Open the tailgate.
Close the tailgate automatically with the keyless transmitter or inside tailgate switch.
Turn the ignition switch to LOCK (0) and then back to ON (II).
Clear the DTCs with the HDS.
Check for DTCs with the HDS.
Is DTC B1388 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 drive unit.
Turn the ignition switch to LOCK (0).
Disconnect power tailgate control unit connector A(5P).
Disconnect drive unit connector A (2P).
Check for continuity between body ground and power tailgate control unit connector A (5P) terminals No. 3 and No. 5 individually.

Fig 1: Checking Continuity Between Body Ground And Connector (5P) Terminals No. 3 And No. 5
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 10.
Reconnect drive unit connector A (2P).
Connect battery power to the power tailgate control unit connector A (5P) terminal No. 3 (or No. 5) and ground the terminal No. 5 or (No. 3).

Fig 2: Identifying Connector (5P) Terminals Connection With Battery
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the power tailgate motor operation.
Does the motor run normally?

YES -Go to step 13.

NO -Faulty power tailgate motor, replace the drive unit.
Disconnect power tailgate control unit connector B (20P).
Disconnect drive unit connector B (8P).
Check for continuity between body ground and power tailgate control unit connector B (20P) terminals No. 9 and No. 20 individually.

Fig 3: Checking Continuity Between Body Ground And Connector B (20P) Terminals No. 9 And No. 20
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair a short to ground in the wire.

NO -Go to step 16.
Reconnect drive unit connector B (8P).
Connect battery power to power tailgate control unit connector B (20P) terminal No. 9 and ground the terminal No. 20. Check for clutch operation.

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

Can you hear the clutch operate?

YES -Go to step 18.

NO -Faulty power tailgate clutch, replace the drive unit.
Measure the voltage between power tailgate control unit connector A (5P) terminal No. 2 and body ground.

Fig 5: Measuring Voltage Between Connector (5P) Terminal No. 2 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 19.

NO -Check the No. 11 (40 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 the power tailgate control unit.
Measure the voltage between power tailgate control unit connector B (20P) terminal No. 12 and body ground.

Fig 6: 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 20.

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 the power tailgate control unit.
Check for continuity between body ground and power tailgate control unit connector A (5P) terminals No. 1 and No. 4 individually.

Fig 7: Checking Continuity Between Body Ground And Connector (5P) Terminals No. 1 And No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Replace the power tailgate control unit.

NO -Repair an open in the wire or poor ground (G701).