NO.9 FAST IDLE/RUNS ON [MZR 2.0, MZR 2.5]

id0103e1801500

9

FAST IDLE/RUNS ON

DESCRIPTION

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

•  The engine runs after the ignition is off.

POSSIBLE CAUSE

•  ECT sensor malfunction

•  Air leakage from intake air system

•  Throttle body malfunction

•  APP sensor malfunction

•  Cruise control system operation improperly

•  Improper load signal input

•  Improper operation of electronic throttle control system

•  PCM malfunction

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

Diagnostic procedure

STEP	INSPECTION	RESULTS	ACTION
1	Access ECT PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 2.0, MZR 2.5].) Start and warm up the engine to normal operating temperature. Is the ECT PID value 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 the symptom troubleshooting “NO.17 COOLING SYSTEM CONCERNS-OVERHEATING”. (See NO.17 COOLING SYSTEM CONCERNS-OVERHEATING [MZR 2.0, MZR 2.5].) ECT PID is less than 82 °C {180 °F}: • Go to the symptom troubleshooting “NO.18 COOLING SYSTEM CONCERNS-RUNS COLD”. (See NO.18 COOLING SYSTEM CONCERNS-RUNS COLD [MZR 2.0, MZR 2.5].)
2	Retrieve any DTCs. (See ON-BOARD DIAGNOSTIC TEST [MZR 2.0, MZR 2.5].) Are any DTCs present?	Yes	Go to the appropriate DTC inspection. (See DTC TABLE [MZR 2.0, MZR 2.5].)
2		No	Go to the next step.
3	Access the AC_REQ and TR PIDs using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [MZR 2.0, MZR 2.5].) (See ON-BOARD DIAGNOSTIC SYSTEM PID/DATA MONITOR INSPECTION [FS5A-EL].) Are the PID values normal? (See PCM INSPECTION [MZR 2.0, MZR 2.5].)	Yes	Go to the next step.
3		No	AC_REQ PID is not specified: • Inspect the A/C switch, refrigerant pressure sensor, evaporator temperature sensor and fan switch. (See REFRIGERANT PRESSURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER].) (See EVAPORATOR TEMPERATURE SENSOR INSPECTION [FULL-AUTO AIR CONDITIONER].) CPP PID is not specified: • Inspect the CPP switch (MTX). (See CLUTCH PEDAL POSITION (CPP) SWITCH INSPECTION [MZR 2.0, MZR 2.5].) CPP/PNP PID is not specified: • Inspect the neutral switch (MTX). (See NEUTRAL SWITCH INSPECTION [MZR 2.0, MZR 2.5].) TR PID is not specified: • Inspect the following: ― TR switch (ATX) (See TRANSAXLE RANGE (TR) SWITCH INSPECTION [FS5A-EL].) ― Communication between TCM and PCM Repair or replace the malfunctioning part according to the inspection results.
4	Is there air leakage felt or heard at the intake air system components while racing the engine to higher speed?	Yes	Repair or replace the malfunctioning part according to the inspection results.
4		No	Inspect the following: • Electronic throttle control system operation • APP sensor (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [MZR 2.0, MZR 2.5].) Repair or replace the malfunctioning part according to the inspection results.
5	• Verify the test results. ― If normal, return to the diagnostic index to service any additional symptoms. (See SYMPTOM DIAGNOSTIC INDEX [MZR 2.0, MZR 2.5].) ― If a malfunction remains, inspect the related Service Information perform repair or diagnosis. • If the vehicle repaired, troubleshooting is completed. • If the vehicle not repaired or additional diagnostic information not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [MZR 2.0, MZR 2.5].)