Detroit DD16 GHG14 (2014-16) Fault Code: SPN 84 FMI 21 (MCM) Vehicle Speed Sensor Failure

DESCRIPTION:
Vehicle speed sensor rationality.

MONITORED PARAMETER:
Vehicle Speed Sensor (VSS).

TYPICAL ENABLING CONDITIONS:
1. Rpm greater than 1500.
2. Torque demand on.

MONITOR SEQUENCE:
None

EXECUTION FREQUENCY:
Continuous when enabling conditions met.

TYPICAL DURATION:
10 seconds

DASH LAMPS:
MIL

ENGINE REACTION:
None

VERIFICATION:
1. Rpm greater than 1500.
2. Torque demand on.

NOTE: If codes for other modules are present, fix those first.

PROBABLE CAUSES:
1. Improper programming of the CPC (Common Powertrain Controller).
2. Other failed modules on the truck (Transmission, ABS, Cab controller, etc…).
3. Battery/battery cable issues, or electical issue on truck.
4. Vehicle speed sensor.
5. Vehicle speed sensor harness/connector.