This instruction show you guide on how to solve Detroit DD13 engine trouble code SPN 84 FMI 21 (CPC) vehicle speed sensor erratic.
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DESCRIPTION:
Vehicle speed sensor erratic.
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 electrical issue on truck.
4 Vehicle speed sensor.
5 Vehicle speed sensor harness/connector.
