DTC U2001: Reduced System Function: Description
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The ABS module incorporates a function for testing the vehicle on a dynamometer to prevent wheel speed sensor DTCs from setting during testing. The PCM sends a message to the ABS module when the vehicle is setup for testing. When the ABS module receives this message it knows to ignore discrepancies between the front and rear wheel speed sensors.
The ABS module exits the test mode automatically when the PCM sends the exit message, the ignition is set to OFF, either of the nondriven wheels exceeds 20 km/h (12 mph) or a wheel speed sensor DTC is detected on any wheel speed sensor.