NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [L8, LF]

id0103a0802400

18

COOLING SYSTEM CONCERNS-RUNS COLD
DESCRIPTION
•  Engine does not reach normal operating temperature.
POSSIBLE CAUSE
•  Improper operation of cooling fan control system
•  Thermostat malfunction
•  ECT sensor malfunction
•  Instrument cluster malfunction
•  PCM 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.
Repair or replace the malfunctioning part according to the inspection results.
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 [L8, LF].)
No
Go to the next step.
3
Perform the Cooling Fan Control System Inspection.
(See ENGINE CONTROL SYSTEM OPERATION INSPECTION [L8, LF].)
Does the cooling fan control system work properly?
Yes
Go to the next step.
No
Repair or replace the malfunctioning part according to the inspection results.
4
Remove the thermostat and inspect operation.
(See THERMOSTAT REMOVAL/INSTALLATION [L8, LF].)
(See THERMOSTAT INSPECTION [L8, LF].)
Is there any malfunction?
Yes
Replace the thermostat.
(See THERMOSTAT REMOVAL/INSTALLATION [L8, LF].)
No
Go to the next step.
5
Connect the M-MDS to the DLC-2.
Perform the PID/DATA Monitor and Record Procedure and access the ECT PID.
(See ON-BOARD DIAGNOSTIC TEST [L8, LF].)
Inspect for both ECT PID and temperature gauge on instrument cluster readings.
Is the ECT PID value same as temperature gauge on instrument cluster?
Yes
Go to the next step.
No
Access the ECT PID.
Inspect both the ECT PID and the low engine coolant temperature indicator light condition.
•  If the low engine coolant temperature indicator light on the instrument cluster indicates turned off but the ECT PID is not the same as the low engine coolant temperature indicator light condition:
―  Inspect the ECT sensor.
•  If the low engine coolant temperature indicator light indication on the instrument cluster illuminates but the ECT PID is normal:
―  Inspect the instrument cluster.
Repair or replace the malfunctioning part according to the inspection results.
6
Verify test results.
•  If normal, return to diagnostic index to service any additional symptoms.
•  If malfunction remains, inspect related Service information perform repair or diagnosis.
―  If vehicle repaired, troubleshooting completed.
―  If vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [L8, LF].)