P0507

DTC P0507: Idle Control System RPM Higher Than Expected

Idle Air Control (IAC) Motor Circuit Part 1:

Idle Air Control (IAC) Motor Circuit Part 2:

CIRCUIT OPERATION
- The idle air control motor power is supplied from the MFI relay (terminal No.4).
- The ECM (terminals No.14, No.15, No.28, No.29) drives the stepper motor by sequentially turning "ON" the power transistors in the ECM and providing ground to the idle air control motor (terminals No.1, No.3, No.4, No.6).

TECHNICAL DESCRIPTION
- The amount of air taken in during idling is regulated by the opening and closing of the servo valve located in the air passage that bypasses the throttle body.
- If there is a malfunction of the IAC system, the actual engine speed will not be identical to the target engine speed.
- 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
- Exhaust gas recirculation (EGR) system monitor
- Fuel system monitor

Sensor (The sensor below is determined to be normal)
- Volume 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
- Vehicle speed has reached 1.5 km/h (1 mph) or more at least once.
- Under the closed loop idle speed control.
- Engine coolant temperature is higher than 77 degrees C (171 degrees 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 degree C (14 degrees F).
- 13 seconds have elapsed from the start of the previous monitoring.
- Target idle air control motor position is 0 steps.

Judgment Criterion
- Actual idle speed has continued to be higher than the target idle speed by 200 r/min (300 r/min*) or more for 12 seconds.

*: Specs in parentheses are applicable if the maximum air temperature during the previous operation was more than 45 degrees C (113 degrees F).

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 18. OBD-II Drive Cycle Pattern Lists

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Intake system vacuum leak.
- Idle air control motor failed.
- Open or shorted idle air control motor circuit, harness damage, or connector damage.
- ECM failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
- MB991709: Test Harness Set

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. Set scan tool MB991958, read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the diagnostic trouble code other than P0507 output?

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

NO: Go to Step 2.

STEP 2. Check for intake system vacuum leaks.

Q: Are there any abnormalities?

YES: Repair or replace it. Then go to Step 14.

NO: Go to Step 3.

STEP 3. Check harness connector B-104 at idle air control motor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 4.

NO: Repair or replace it. Then go to Step 14.

STEP 4. Measure the idle air control motor coil resistance.

1. Disconnect the idle air control motor connector B-104.

2. Measure the resistance between idle air control motor connector terminal No.2 and either terminal No.1 or terminal No.3.

Standard value: 28 - 33 Ohms [at 20 degrees C (68 degrees F)]

3. Measure the resistance between idle air control motor connector terminal No.5 and either terminal No.4 or terminal No.6.

Standard value: 28 - 33 Ohms [at 20 degrees C (68 degrees F)]

Q: Is the measured resistance between 28 and 33 Ohms [at 20 degrees C (68 degrees F)]?

YES: Go to Step 5.

NO: Replace the idle air control motor. Then go to Step 14.

STEP 5. Measure the power supply voltage at idle air control motor harness side connector B-104.

1. Disconnect connector B-104 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.

3. Measure the voltage between terminals No.2, No.5 and ground.
- Voltage should be battery positive voltage.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 7.

NO: Go to Step 6.

STEP 6. Check harness connector B-12X at MFI relay for damage.

Q: Is the harness connector in good condition?

YES: Repair harness wire between MFI relay connector B-12X (terminal No.4) and idle air control motor connector B-104 (terminals No.2, No.5) because of open circuit or short circuit to ground. Then go to Step 14.

NO: Repair or replace it. Then go to Step 14.

STEP 7. Measure the power supply voltage at ECM connector C-121 by backprobing.

1. Do not disconnect connector C-121.

2. Measure the voltage between terminals (No.14, No.15, No.28, No.29) and ground by backprobing.
- The voltage is 1 V or lower for approximately 3 seconds, then changes to the battery positive voltage when the Ignition switch is turned from the "LOCK" (OFF) position to the "ON" position.

3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the measured voltage within the specified range?

YES: Go to Step 10.

NO: Go to Step 8.

STEP 8. Check harness connector C-121 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 9.

NO: Repair or replace it. Then go to Step 14.

STEP 9. Check for open circuit and short circuit to ground between idle air control motor connector B-104 and ECM connector C-121.

STEP 10. Check harness connector C-121 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 11.

NO: Repair or replace it. Then go to Step 14.

STEP 11. Check the idle air control motor operation using special tool MB991709.

1. Remove the idle air control motor.

2. Connect special tool MB991709 to the idle air control motor. (All terminals should be connected.)
3. Use the jumper wires to connect terminal No.2 of the idle air control motor connector to the positive battery terminal.

4. Check the ensure that the motor operates when the terminals No.1 and No.3 of the idle air control motor connector are respectively connected to the negative battery terminal using a jumper wire.
- Vibration should be present at each application of voltage to test clip combination.

5. Then, use jumper wires to connect the terminal No.5 of the idle air control motor connector to the positive battery terminal.
6. Check to ensure that the motor operates when terminals No.4 and No.6 of the idle air control motor connector are respectively connected to the negative battery terminal using a jumper wire.
- Vibration should be present at each application of voltage to test clip combination.

7. Install the idle air control motor. Refer to Throttle Body Assembly - Disassembly and Assembly.

Q: Is the idle air control motor operating properly?

YES: Go to Step 12.

NO: Replace the idle air control motor. Then go to Step 14.

STEP 12. Check for harness damage between MFI relay connector B-12X (terminal No.4) and idle air control motor connector B-104 (terminals No.2, No.5).

Q: Is the harness wire in good condition?

YES: Go to Step 13.

NO: Repair it. Then go to Step 14.

STEP 13. Check for harness damage between idle air control motor connector B-104 and ECM connector C-121.

a. Idle air control motor connector B-104 (terminal No.1) and ECM connector C-121 (terminal No.14).
b. Idle air control motor connector B-104 (terminal No.3) and ECM connector C-121 (terminal No.28).
c. Idle air control motor connector B-104 (terminal No.4) and ECM connector C-121 (terminal No.15).
d. Idle air control motor connector B-104 (terminal No.6) and ECM connector C-121 (terminal No.29).

Q: Is the harness wire in good condition?

YES: Replace the ECM. Then go to Step 14.

NO: Repair it. Then go to Step 14.

STEP 14. 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 18. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0507 set?

YES: Retry the troubleshooting.

NO: The inspection is complete.