DTC B1826: Power Seat Front Up-down Motor Pulse Error

WARNING: This page is about a different car, the 2009 Acura MDX, 2008 Acura MDX, and 2007 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

DTC B1826 is stored when the front up-down switch is operated more than 1 second after the seat moves to the most up or most down position, even when the system is OK.

Turn the ignition switch to LOCK (0), and then back ON (II).
Clear the DTCs with the HDS.
Operate the power seat adjustment switch in all directions for more than 1 second each.
Check for the DTCs with the HDS.
Is DTC B1826 indicated?

YES - Go to step 5.

NO - Intermittent failure, the front up-down motor/ position sensor is OK at this time. Check for loose or poor connections at the power seat control unit connectors.
Check for DTCs with the HDS.
Is DTC B1836 also indicated?

YES - Troubleshoot DTC B1836 first.

NO - Go to step 6.
Check for DTCs with the HDS.
Are DTCs B1825, B1827 and/or B1828 also indicated?

YES - Go to step 17.

NO - Go to step 7.
Turn the ignition switch to LOCK (0), and then back ON (II).
Operate the front up-down switch for 2 seconds, and check the front up-down motor operation.
Does the front up-down motor run smoothly?

YES - Go to step 9.

NO - Go to step 26.
Turn the ignition switch to LOCK (0).
Disconnect power seat control unit connector A (40P).
Disconnect the front up-down position sensor 4P connector.
Check for continuity between the power seat control unit connector A (40P) No. 12 and No. 29 terminals and the front up-down position sensor 4P connector No. 2 and No. 3 terminals respectively.

Fig 1: Identifying Continuity Between No. 12 And No. 29 Terminals And No. 2 And No. 3 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 13.

NO - Repair open in the wire.
Check for continuity between the power seat control unit connector A (40P) No. 12 terminal and body ground.

Fig 2: Identifying Continuity Between Power Seat Control Unit Connector A (40P) No. 12 Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is Mere continuity?

YES - Repair short to ground in the wire.

NO - Go to step 14.
Reconnect power seat control unit connector A (40P).
Turn the ignition switch ON (II).
Measure the voltage between the front up-down position sensor 4P connector No. 2 (+) and No. 3 (-) terminals.

Fig 3: Identifying Voltage Between Front Up-Down Position Sensor 4P Connector No. 2 And No. 3 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 5 V?

YES - Faulty front up-down position sensor, replace the front up-down motor.

NO - If there is no voltage, replace the power seat control unit. If there is battery voltage, repair a short in the wire (sensor line).
Turn the ignition switch to LOCK (0).
Disconnect power seat control unit connector A (40P).
Disconnect the front up-down position sensor 4P connector.
Check for continuity between the power seat control unit connector A (40P) No. 15 and No. 29 terminals and the front up-down position sensor 4P connector No. 1 and No. 3 terminals respectively.

Fig 4: Identifying Continuity Between No. 15 And No. 29 Terminals And No. 1 And No. 3 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 21.

NO - Repair open in the wire.
Disconnect the 4P connector from the slide position sensor and the rear up-down position sensor, then disconnect the recline motor/lumbar support motor 8P connector.
Check for continuity between body ground and the front up-down position sensor 4P connector No. 1 terminal.

Fig 5: Identifying Continuity Between Body Ground And Front Up-Down Position Sensor 4P Connector No. 1 Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to ground in the wire.

NO - Go to step 23.
Reconnect power seat control unit connector A (40P).
Turn the ignition switch ON (II).
Measure the voltage between the power seat control unit connector A (40P) No. 15 and No. 29 terminals.

Fig 6: Identifying Voltage Between Power Seat Control Unit Connector A (40P) No. 15 And No. 29 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage when the front up-down switch is operated?

YES - Replace the front up-down motor/position sensor.

NO - Replace the power seat control unit.
Turn the ignition switch to LOCK (0).
Disconnect power seat control unit connector B (18P).
Disconnect the front up-down motor 2P connector.
Check for continuity between the power seat control unit connector B (18P) No. 6 and No. 16 terminals and the front up-down motor 2P connector No. 1 and No. 2 terminals respectively.

Fig 7: Identifying Continuity Between No. 6 And No. 16 Terminals And No. 1 And No. 2 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 30.

NO - Repair open in the wire.
Check for continuity between body ground and the front up-down motor 2P connector No. 1 and No. 2 terminals individually.

Fig 8: Identifying Continuity Between Body Ground And Front Up-Down Motor 2P Connector No. 1 And No. 2 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair short to ground in the wire.

NO - Go to step 31.
Test the front up-down motor (see SLIDE MOTOR, FRONT UP-DOWN MOTOR, REAR UP-DOWN MOTOR ).
Is the motor OK?

YES - Replace the power seat control unit.

NO - Replace the front up-down motor/position sensor.