#
NO.18 COOLING SYSTEM CONCERNS-RUNS COLD

BHE010300103W20

18 | COOLING SYSTEM CONCERNS -RUNS COLD
--- | ---
DESCRIPTION | The engine takes excessive time to reach the normal operating temperature.
POSSIBLE CAUSE | • Thermostat malfunction • Eccentric shaft bypass malfunction (stuck open) • Cooling fan system malfunction

Diagnostic procedure

STEP | INSPECTION | RESULTS | ACTION
--- | --- | --- | ---
1 | Is the customer complaint "Lack of passenger compartment heat" only? | Yes | Inspect the A/C and heater system.
No | Go to the next step.
2 | Does the engine speed continue at fast idle? | Yes | Go to the symptom troubleshooting "No.9 Fast idle/runs on". (See NO.9 FAST IDLE/RUNS ON.)
No | Go to the next step.
3 | Remove the thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION.) (See THERMOSTAT INSPECTION.) Is the thermostat normal? | Yes | Go to the next step.
No | Replace the thermostat.
4 | Inspect the cooling fan control system operation. (See Cooling Fan Control System Inspection.) Does the cooling fan control system work properly? | Yes | Go to the next step.
No | Repair or replace the malfunctioning part.
5 | Access the ECT PID. Inspect readings on both the ECT PID and the temperature gauge on the instrument cluster. Is the ECT PID indication the same as the temperature gauge readings? | Yes | Inspect the eccentric shaft bypass valve. (See Engine Workshop Manual.)
No | If the temperature gauge is in the normal range but the ECT PID is not the same as the temperature gauge reading, inspect the ECT sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION.) If the temperature gauge on the instrument cluster indicates the cold range but the ECT PID is normal, inspect the temperature gauge and the sending unit. (See Water temperature gauge.)
6 | Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. • If the malfunction remains, inspect the related Service Information and perform the repair or diagnosis.