Detroit DD16 GHG14 (2014-16) Fault Code: SPN 1639 FMI 2 (MCM) Fan Speed Error

DESCRIPTION:
This code sets when a fan speed deviation is detected.

MONITORED PARAMETER:
Fan speed sensor.

TYPICAL ENABLING CONDITIONS:
Always enabled

MONITOR SEQUENCE:
None

EXECUTION FREQUENCY:
Always enabled

TYPICAL DURATION:
Two seconds

DASH LAMPS:
CEL

ENGINE REACTION:
None

VERIFICATION:
Engine running with fan engaged.

NOTE: If 1071-5 or 647-5 active, repair the wiring between pin 91 (from the 120 pin ECM connector) and the fan and the jake brake solenoids.

PROBABLE CAUSES:
1. Coolant loss.
2. Thermostat failure.
3. Bloackage in radiator and charge air cooler.
4. Fan belt condition.
5. Proper location of fan shroud.
6. Proper radiator hose condition.
7. Fan failure.
8. Short between fan speed sensor and ECM.
9. Fan drive failure.