Cummins ISB CM850 (2003-06) Fault Code: 242 PID: 84 SPN: 84 FMI: 10 Vehicle Speed Sensor Circuit Tampering Has Been Detected – Abnormal Rate of Change. Invalid or inappropriate vehicle speed signal. Signal indicates an intermittent connection or VSS tampering.

Cummins ISB CM850 (2003-06) Fault Code: 242 PID: 84 SPN: 84 FMI: 10 Vehicle Speed Sensor Circuit Tampering Has Been Detected – Abnormal Rate of Change. Invalid or inappropriate vehicle speed signal. Signal indicates an intermittent connection or VSS tampering.

Verify that the feature settings for the vehicle speed sensor anti-tampering (Fault Code 242), application type and automatic transmission are set correctly. If any of these are set incorrectly for your specific vehicle and application, Fault Code 242 could occur erroneously.

Driving techniques such as driving for extended periods of time in lower gears can log Fault Code 242. Fault Code 242 can be logged if the driver attempts to defeat the road speed governor by repeatedly cycling the keyswitch.

Once the speed signal has been restored the fault code will go inactive once the keyswitch is on for 30 seconds and the ECM senses zero vehicle and engine speed.

Possible repairs:

1)Remove the tampering device. Install the sensor correctly or remove the external device.
2)Repair or replace the OEM harness.
3)Replace the ECM.