DTC B2140: Headlight Leveling Motor Signal Circuit Error

Clear the DTCs with the HDS.
Turn the ignition switch OFF, and then back ON (II).
Turn the headlight switch ON.
Check for DTCs with the HDS.
Is DTC B2140 indicated?

YES - Go to step 5.

NO - Intermittent failure, the adaptive front lighting system is OK at this time. Check for loose or poor connections at the headlight leveling motor connector and at the adaptive front lighting control unit connector.
Turn the ignition switch OFF.
Disconnect the adaptive front lighting control unit 40P connector.
Disconnect the left and right headlight leveling motor 3P connectors.
Check for continuity between adaptive front lighting control unit 40P connector terminal No. 36 and body ground.

Fig 1: Checking Continuity Between Adaptive Front Lighting Control Unit 40P Connector Terminal No. 36 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Repair a short to ground in the wire.

NO - Go to step 9.
Connect headlight leveling motor 3P connector terminal No. 2 to body ground with a jumper wire.

Fig 2: Connecting Headlight Leveling Motor 3P Connector Terminal No. 2 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check for continuity between adaptive front lighting control unit 40P connector terminal No. 36 and body ground.

Fig 3: Checking Continuity Between Adaptive Front Lighting Control Unit 40P Connector Terminal No. 36 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 11.

NO - Repair an open in the wire.
Reconnect the adaptive front lighting control unit 40P connector.
Reconnect both headlight leveling motor 3P connectors.
Turn the ignition switch ON (II).
Measure the voltage between adaptive front lighting control unit 40P connector terminals No. 36 (+) and No. 30 (-).

Fig 4: Measuring Voltage Between Adaptive Front Lighting Control Unit 40P Connector Terminals No. 36 (+) And No. 30 (-)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 0.5-4.5 V?

YES - Faulty adaptive front lighting control unit, replace it and do the adaptive front lighting control unit learning procedure (see ADAPTIVE FRONT LIGHTING CONTROL UNIT LEARNING PROCEDURE ).

NO - Do the headlight leveling motor test (see HEADLIGHT LEVELING MOTOR TEST ).