On-Board Diagnostics (OBD)

ON-BOARD DIAGNOSTICS (OBD)

COOLING SYSTEM RELATED DIAGNOSTICS

The Engine Control Module (ECM) 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 electronically controlled viscous fan clutch circuit, a Diagnostic Trouble Code (DTC) can be set.
- Coolant temperature sensor circuit problems can set a DTC.

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 ECM memory for eventual display to the service technician.

ACCESSING DIAGNOSTIC TROUBLE CODES

To read DTC's and to obtain cooling system data, Refer to EMISSIONS CONTROL.

ERASING TROUBLE CODES

After the problem has been repaired, use the scan tool to erase a DTC.