Inspection Procedure 9
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:)
- Malfunction of the IAC system.
- Malfunction of the throttle body.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
STEP 1.Using scan tool MB991502, read the diagnostic trouble code (DTC).
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 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.
Q: Is the DTC is output?
YES: Refer to Diagnostic Trouble Code Chart.
NO: Go to Step 2.
STEP 2.Check the idle air control (IAC) motor operation sound.
1. Check that the engine coolant temperature is 20 °C (68 °F) or below.
NOTE: Disconnecting the engine coolant temperature sensor connector and connecting the harness side of the connector to another engine coolant temperature sensor that is at 20 °C (68 °F) or below is also okay.
2. Check the operation sound of the IAC motor can be heard after the ignition is switched to the "ON" position (but without starting the engine).
- An operation sound should be heard.
3. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Did you hear the operation sound?
YES: Go to Step 3.
NO: Refer to DTC P0506 - Idle Control System RPM Lower Than Expected <3.0L Engine> or DTC P0506 - Idle Control System RPM Lower Than Expected <3.5L Engine>, DTC P0507 - Idle Control System RPM Higher Than Expected <3.0L Engine> or DTC P0507- Idle Control System RPM Higher Than Expected <3.5L Engine>.
STEP 3.Using scan tool MB991502, check data list.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Check the following items in the data list. Refer to Data List Reference Table.
a. Item 26: Closed Throttle Position Switch <3.0L Engine>.
b. Item 21: Engine Coolant Temperature Sensor.
c. Item 28: A/C Switch.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are they operating properly?
YES: Go to Step 4.
NO: Repair or replace. Then confirm that the malfunction symptom is eliminated.
STEP 4.Adjust the basic Idle speed. Refer to Basic Idle Speed Adjustment for the adjustment procedure.
Standard value: 700 ± 50 r/min
Q: Is the Idle speed normal?
YES: Carry out the following cleaning or adjustment.
a. Clean the throttle valve area.
b. Check and adjust the fixed SAS <3.0L Engine>
NO: The check is completed.