Description of On-Board Diagnostics

COOLING SYSTEM RELATED DIAGNOSTICS
The Powertrain Control Module (PCM) has been programmed to monitor certain cooling system components:
- If the engine has remained cool for too long a period, such as with a stuck open thermostat, a Diagnostic Trouble Code (DTC) can be set.
- If an open or shorted condition has developed in the relay circuit controlling the electric radiator fan, a Diagnostic Trouble Code (DTC) can be set.

If the problem is sensed in a monitored circuit often enough to indicated an actual problem, a DTC is stored. The DTC will be stored in the PCM memory for eventual display to the service technician. Refer to Powertrain Management for the correct procedures.