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NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZR-CD (RF Turbo)]

BME010300000W53

18 | COOLING SYSTEM CONCERNS-RUNS COLD
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DESCRIPTION | • Engine takes excessive period for reaching normal operating temperature.
POSSIBLE CAUSE | • Thermostat malfunction • Main fan system malfunction • Additional fan system malfunction • Coolant heater system malfunction

Diagnostic Procedure

STEP | INSPECTION | RESULTS | ACTION
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1 | Is customer complaint "Lack of passenger compartment heat"? | Yes | Inspect A/C heater system.
No | Go to next step.
2 | Does engine speed continue at fast idle? | Yes | Go to symptom troubleshooting "NO.7 SLOW RETURN TO IDLE".
No | Go to next step.
3 | Connect WDS or equivalent to DLC-2. Access ECT PID. Inspect for both ECT PID and temperature gauge on instrument cluster readings. Is ECT PID same as temperature gauge reading? | Yes | Go to next step.
No | If temperature gauge on instrument cluster indicates normal range but ECT PID is not same as temperature gauge reading, inspect ECT sensor. If temperature gauge on instrument cluster indicates cold range but ECT PID is normal, inspect temperature gauge and heat gauge unit.
4 | Remove thermostat and inspect operation. (See THERMOSTAT REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].) (See THERMOSTAT INSPECTION.) Is thermostat okay? | Yes | Go to next step.
No | Replace thermostat.
5 | Inspect main fan and additional fan operations. If both or either fan operate normally, inspect for following: • Main fan relay is stuck closed • Additional fan relay is stuck closed • Short to GND between main fan relay and PCM terminal 76
• Circuit between main fan relay and fan motor short to battery supply line
• Additional fan relay is stuck closed
• Short to GND between additional fan relay and PCM terminal 102
• Circuit between additional fan relay and fan motor short to battery supply line
• Short to GND between A/C switch and PCM terminal 84
Are all circuits okay?
Yes
Perform coolant heater system inspection.
Repair or replace malfunctioning part according to coolant heater system operation results.
No | Repair or replace as necessary.
6 | Verify test results. • If okay, return to diagnostic index to service any additional symptoms. • If malfunction remains, replace PCM. (See PCM REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)