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Inspection procedure 8: Idle speed is high (improper idle speed)
 
 
 
 
COMMENT
  • In such cases as the above, the cause is probably that the intake air volume during idle is too great.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case:)
  • Engine coolant temperature sensor signal failed.
  • Accelerator pedal position sensor (main) signal failed.
  • Accelerator pedal position sensor (sub) signal failed.
  • A/C switch signal failed.
  • Evaporative emission control system failed.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is any DTC set?
Refer to, Diagnostic Trouble Code Chart .
Go to Step 2.
 
STEP 2. Using scan tool (M.U.T.-III), check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 6: Engine Coolant Temperature Sensor
  2. Item 11: Accelerator Pedal Position Sensor (main)
  3. Item 12: Accelerator Pedal Position Sensor (sub)
  4. Item 76: A/C Switch
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
Refer to GROUP 17, Emission Control - Evaporative Emission Control System - Evaporative Emission Purge Solenoid Check .
Repair or replace it. Then confirm that the malfunction symptom is eliminated.