DTC 21-1, 21-2, 22-1, 22-2: Front Wheel Speed Sensors

NOTE: Before you troubleshoot, review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Test-drive the vehicle at 25 mph (40km/h) or more, while keeping the engine speed below 2, 500 rpm for at least 30 seconds.
NOTE: Be careful not to overheat the rear differential clutch system.
Check for DTCs with the HDS.
Is DTC 21-1, 21-2, 22-1 and/or 22-2 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. ■
Check for DTCs in the VSA system with the HDS.
Are there any VSA DTCs indicated?

YES -go to the indicated DTCs troubleshooting. ■

NO -Go to step 6.
Turn the ignition switch to LOCK (0).
Raise the vehicle on a lift, and make sure it is securely supported.
Spin the rear wheels by hand, and check for rear brake drag.
Are the rear brakes dragging?

YES -Inspect and repair the cause for rear brake drag (see RAPID BRAKE PAD WEAR (BRAKE DRAG), VEHICLE VIBRATION (AFTER A LONG DRIVE), OR HIGH, HARD BRAKE PEDAL ).

NO -Go to step 9.
Turn the ignition switch to ON (II).

Measure the voltage between VTM-4 control unit connector terminals A7 and A9 to body ground while rotating the appropriate wheel (1 rotation/second).

VOLTAGE REFERENCE

DTC	Appropriate Terminal
21-1, 21-2 (Left-front)	A9
22-1, 22-2 (Right-front)	A7

Fig 1: Measuring Voltage Between VTM-4 Control Unit Connector Terminals A7 And A9 To Body Ground

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 2.0 V to 3.0 V?

YES -Go to step 17

NO -Go to step 11.

Turn the ignition switch to LOCK (0).
Disconnect VTM-4 control unit connector A (22P) and the VSA modulator-control unit 46P connector.
Check for continuity between VTM-4 control unit connector terminals A7 and A9 to body ground respectively.

Fig 2: Checking Continuity Between VTM-4 Control Unit Connector Terminals A7 And A9 To Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Repair short to ground in the wire between VTM-4 control unit (A7 and/or A9) and the VSA modulator-control unit. ■

NO -Go to step 14.

Connect VTM-4 control unit connector terminals A7 and A9 to body ground with jumper wires.

VOLTAGE REFERENCE

DTC	Appropriate Terminal
21-1, 21-2 (Left-front)	A9
22-1, 22-2 (Right-front)	A7

Fig 3: Connecting VTM-4 Control Unit Connector Terminals A7 And A9 To Body Ground

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Check for continuity between body ground and the appropriate VSA modulator-control unit 46P connector terminal (see table).

CONTINUITY REFERENCE

Fig 4: Checking Continuity Between VSA Modulator-Control Unit 46P Connector Terminals And Body Ground

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 16.

NO -Repair open in the wire between VTM-4 control unit (A7 and/or A9) and the VSA modulator-control unit. ■

Reconnect all connectors.
Check for poor connections or loose terminals at the VTM-4 control unit and the VSA modulator-control unit connectors. If the connections are OK, substitute a know-good VTM-4 control unit (see VTM-4 CONTROL UNIT REPLACEMENT ) and recheck. If the symptom/indication goes away with the know-good VTM-4 control unit, replace the original VTM-4 control unit (see VTM-4 CONTROL UNIT REPLACEMENT ), then Go to step 18.
Test-drive the vehicle at 25 mph (40km/h) or more, while keeping the engine speed below 2, 500 rom for at least 30 seconds.
NOTE: Be careful not to overheat the rear differential clutch system.
Check for DTCs with the HDS.
Is DTCs 21-1, 21-2, 22-1 and/or 22-2 indicated?

YES -Replace the VSA modulator-control unit (see VSA MODULATOR-CONTROL UNIT REMOVAL AND INSTALLATION ). ■

NO -Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.