NO.9 FAST IDLE/RUNS ON [MZI-3.7]

id0103d2801500

9

FAST IDLE/RUNS ON

DESCRIPTION

•  The engine speed continues at fast idle after warm-up.

•  The engine runs after the ignition switch is turned off.

POSSIBLE CAUSE

•  CHT sensor malfunction

•  Air leakage from intake-air system

•  Throttle body malfunction

•  Accelerator pedal position sensor misadjustmentwn

•  Cruise control system operation improperly

•  Improper load signal input

•  Improper operation of electronic throttle control system

9	FAST IDLE/RUNS ON
DESCRIPTION	• The engine speed continues at fast idle after warm-up. • The engine runs after the ignition switch is turned off.
POSSIBLE CAUSE	• CHT sensor malfunction • Air leakage from intake-air system • Throttle body malfunction • Accelerator pedal position sensor misadjustmentwn • Cruise control system operation improperly • Improper load signal input • Improper operation of electronic throttle control system

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Connect the M-MDS to the DLC-2. Access ECT PID. Start and warm up engine to normal operating temperature. Is ECT PID between 82—112°C {180—234°F}?	Yes	Go to the next step.
1		No	ECT PID is higher than 112°C {234°F}: Go to symptom troubleshooting “No.17 Cooling system concerns - Overheating”. ECT PID is less than 82°C {180°F}: Go to symptom troubleshooting “No.18 Cooling system concerns - Runs cold”.
2	Connect the M-MDS to the DLC-2. Turn the ignition switch to the ON position (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [MZI-3.7].)
2		No	No DTC is displayed: Go to the next step.
3	Access and monitor PSP and TR PIDs. Are PIDs values normal? (See PCM INSPECTION [MZI-3.7].)	Yes	Go to the next step.
3		No	If the AC_REQ PID is not normal: • Inspect A/C switch, refrigerant pressure switch, and fan switch, and related wiring harness for vibration or intermittent open/short circuit. If the TR PID is not normal: • Inspect TR switch and related wiring harness for vibration or intermittent open/short circuit. If the PSP PID is not normal: • Inspect power steering switch and related wiring harness for vibration or intermittent open/short circuit.
4	Is there air leakage felt or heard at intake-air system components while racing engine to higher speed?	Yes	Repair or replace parts if necessary.
4		No	Inspect the following: • Electronic throttle control system operation • Accelerator pedal position sensor
5	• Verify test results. ― If normal, return to diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZI-3.7].) ― If malfunction remains, inspect related Service Information and perform repair or diagnosis. • If vehicle is repaired, troubleshooting completed. • If vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZI-3.7].)