On-Board Diagnostics (Obd); Preliminary Checks - Dodge 2000 DURANGO Service Manual

7 - 10 COOLING SYSTEM
DIAGNOSIS AND TESTING

ON-BOARD DIAGNOSTICS (OBD)

COOLING SYSTEM RELATED DIAGNOSTICS
The powertrain control module (PCM) has been
programmed to monitor certain cooling system com-
ponents:
• If the engine has remained cool for too long a
period, such as with a stuck open thermostat, a Diag-
nostic 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 mem-
ory for eventual display to the service technician.
Refer to Group 25, Emission Control Systems for the
correct procedures.
ACCESSING DIAGNOSTIC TROUBLE CODES
To read DTC's and to obtain cooling system data,
refer to Group 25, Emission Control Systems for the
correct procedures.
ERASING TROUBLE CODES
After the problem has been repaired, use the DRB
scan tool to erase a DTC. Refer to the appropriate
Powertrain Diagnostic Procedures service manual for
operation of the DRB scan tool.
DRB SCAN TOOL
For operation of the DRB scan tool, refer to the
appropriate Powertrain Diagnostic Procedures ser-
vice manual.

PRELIMINARY CHECKS

ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
PROLONGED IDLE, VERY HIGH AMBIENT
TEMPERATURE, SLIGHT TAIL WIND AT IDLE,
SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED,
OR STEEP GRADES.
Driving techniques that avoid overheating are:
• Idle with A/C off when temperature gauge is at
end of normal range.
• Increase engine speed for more air flow is recom-
mended.
(1) TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
(2) AIR CONDITIONING; ADD-ON OR AFTER
MARKET:
A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer's specifications.
(3) RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
• Engine adjustments (incorrect timing)
• Slipping engine accessory drive belt(s)
• Brakes (possibly dragging)
• Changed parts. Incorrect water pump, or pump
rotating in wrong direction due to belt not correctly
routed
• Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, refer to following Cooling System Diagnosis
charts.
These charts are to be used as a quick-reference
only. Refer to the group text for information.
DN