Description of On-Board Diagnostics

ON-BOARD DIAGNOSTICS (OBD)
COOLING SYSTEM RELATED DIAGNOSTICS
The Powertrain Control Module (PCM) has been programmed to monitor the certain following 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 DTC can be set.
If the problem is sensed in a monitored circuit often enough to indicate an actual problem, a DTC is stored. The DTC will be stored in the PCM memory for eventual display to the service technician.