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.

ACCESSING DIAGNOSTIC TROUBLE CODES
To read DTC's and to obtain cooling system data, Refer to Powertrain Management.

ERASING TROUBLE CODES
After the problem has been repaired, use the DRB scan tool to erase a DTC. Refer to the appropriate service information for operation of the DRB scan tool.