P1506

DTC P1506: Idle Control System RPM Lower Than Expected at Low Temperature

TECHNICAL DESCRIPTION
- The amount of air taken in during idling is regulated by the opening and closing of the throttle valve.
- The ECM checks the difference between the actual engine speed and the target engine speed.

DESCRIPTIONS OF MONITOR METHODS
Difference between actual and target idle speed is over the specified value.

MONITOR EXECUTION
Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Misfire monitor
- Fuel system monitor
- Vehicle speed signal monitor

Sensor (The sensor below is determined to be normal)
- Mass airflow sensor
- Engine coolant temperature sensor
- Intake air temperature sensor
- Barometric pressure sensor
- Throttle position sensor

DTC SET CONDITIONS

Logic Flow Chart

Logic Flow Chart:

Check Conditions
- Under the closed loop idle speed control.
- The engine coolant temperature is between 7°C (45°F) and 41°C (106°F).
- Battery positive voltage is higher than 10 volts.
- Barometric pressure is higher than 76 kPa (22.4 in.Hg).
- Intake air temperature is higher than -10°C (14°F).
- More than 3 seconds have elapsed from the previous monitoring.
- Target air flow rate is 29 g/sec (24 L/sec) or more.

Judgment Criterion
- The actual idle speed is more than 100 r/min lower than the target idle speed for 10 seconds.

FAIL-SAFE AND BACKUP FUNCTION
- None

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD- II Drive Cycle

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle valve area is dirty.
- Throttle body assembly failed.
- ECM failed.

DIAGNOSIS

Required Special Tools
- 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).







CAUTION: To 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. After the DTC has been deleted, read the DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the diagnostic trouble code other than P1506 set?

YES : Refer to Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions

NO : Go to Step 2.

STEP 2. Check the throttle body, (throttle valve area)

Q: Is the throttle valve area dirty?

YES : Perform cleaning. Refer to Throttle body (throttle valve area) cleaning. Then go to Step 4.

NO : Go to Step 3.

STEP 3. Replace the throttle body assembly.

1. Replace the throttle body assembly.
2. Carry out test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD- II Drive Cycle
3. Check the diagnostic trouble code (DTC).

Q: Is DTC P1506 set?

YES : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 4.

NO : The inspection is complete.

STEP 4. Test the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 19. OBD- II Drive Cycle
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P1506 set?

YES : Retry the troubleshooting.

NO : The inspection is complete.