[Previous][Next]
Inspection procedure 9: Idle speed is low (improper idle speed)
 
 
 
 
COMMENT
  • In cases such as the above, the cause is probably that the intake air volume during idle is too small.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this case:)
  • Engine coolant temperature sensor signal failed.
  • Torque converter failed.
  • Dirtiness around throttle valve.
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tool:
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: V.C.I.
    • MB991827: USB Cable
    • MB991910: Main Harness A
STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(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 MB991958, check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following item in the data list. Refer to Data List Reference Table .
  1. Item 6: Engine Coolant Temperature Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
Refer to GROUP 23A, Diagnosis - Torque Converter Stall Test .
Repair or replace it. Then confirm that the malfunction symptom is eliminated.