DTC 81-51: Central Processing Unit (CPU) Internal Circuit Malfunction; DTC 81-53: Central Processing Unit (CPU) Internal Circuit Malfunction; DTC 81-55: Central Processing Unit (CPU) Internal Circuit Malfunction; DTC 81-57: Central Processing Unit (CPU) Internal Circuit Malfunction

Turn the ignition switch to ON (II).
Clear the DTC with the HDS.
Test-drive the vehicle.
NOTE: Drive the vehicle on the road, not on a lift.
Check for DTCs with the HDS.
Is DTC 81-51, 81-53, 81-55, or 81-57 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time.
Turn the ignition switch to LOCK (0).
Disconnect the VSA modulator-control unit 37P connector (see Removal step 2 in VSA Modulator-Control Unit Removal and Installation ).
Turn the ignition switch to ON (II).

Measure the voltage between body ground and the appropriate VSA modulator-control unit 37P connector terminals (see table).

VOLTAGE REFERENCE CHART

DTC	VSA Modulator-control Unit 37P Connector Terminals
81-51	No. 19
81-53	No. 22
81-55	No. 9
81-57	No. 20

Fig 1: Measuring Voltage Between Body Ground And VSA Modulator-Control Unit 37P Connector Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there 0.1 V or more?

YES -Repair short to power in the wire between the appropriate wheel speed sensor and the VSA modulator-control unit.