DIAGNOSIS Required Special Tools: • MB991958: Scan Tool (MUT-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).

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 . NO: Go to Step 2.

STEP 2. Check for intake system vacuum leaks. Q: Are there any abnormalities? YES: Go to Step 3. NO: Repair or replace it. Then go to Step 14.

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. Refer to GROUP 00E, Harness Connector Inspection . 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°C (68°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°C (68°F)] Q: Is the measured resistance between 28 and 33 ohms [at 20°C (68°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: Check connector C-105 at intermediate connector for damage, and repair or replace as required. Refer to GROUP 00E, Harness Connector Inspection . If intermediate connector is in good condition, 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. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 14.

STEP 7. Measure the power supply voltage at ECM connector C-121 <M/T> or PCM connector C-120 <A/T> by backprobing.

(1) Do not disconnect connector C-121 <M/T> or C-120 <A/T>.

(2) Measure the voltage between terminals (No. 4, No. 5, No. 17, No. 18) <M/T> or (No. 14, No. 15, No. 28, No. 29) <A/T> and ground by backprobing. • The voltage is 1 volt 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 <M/T> or harness connector C-120 at PCM <A/T> for damage.

Q: Is the harness connector in good condition? YES: Go to Step 9. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . 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 <M/T> or PCM connector C-120 <A/T>.

a.Idle air control motor connector B-104 (terminal No. 1) and ECM connector C-121 (terminal No. 4) <M/T> or PCM connector C-120 (terminal No. 14) <A/T>. b.Idle air control motor connector B-104 (terminal No. 3) and ECM connector C-121 (terminal No. 17) <M/T> or PCM connector C-120 (terminal No. 28) <A/T>. c.Idle air control motor connector B-104 (terminal No. 4) and ECM connector C-121 (terminal No. 5) <M/T> or PCM connector C-120 (terminal No. 15) <A/T>. d.Idle air control motor connector B-104 (terminal No. 6) and ECM connector C-121 (terminal No. 18) <M/T> or PCM connector C-120 (terminal No. 29) <A/T>. Q: Is the harness wire in good condition? YES: Replace the ECM or PCM. Then go to Step 14. NO: Repair it. Then go to Step 14.

STEP 10. Check harness connector C-121 at ECM <M/T> or harness connector C-120 at PCM <A/T> for damage.

Q: Is the harness connector in good condition? YES: Go to Step 11. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . 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 the ensure that the motor operates when the 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 <M/T> or PCM connector C-120 <A/T>.

a.Idle air control motor connector B-104 (terminal No. 1) and ECM connector C-121 (terminal No. 4) <M/T> or PCM connector C-120 (terminal No. 14) <A/T>. b.Idle air control motor connector B-104 (terminal No. 3) and ECM connector C-121 (terminal No. 17) <M/T> or PCM connector C-120 (terminal No. 28) <A/T>. c.Idle air control motor connector B-104 (terminal No. 4) and ECM connector C-121 (terminal No. 5) <M/T> or PCM connector C-120 (terminal No. 15) <A/T>. d.Idle air control motor connector B-104 (terminal No. 6) and ECM connector C-121 (terminal No. 18) <M/T> or PCM connector C-120 (terminal No. 29) <A/T>. Q: Is the harness wire in good condition? YES: Replace the ECM or PCM. Then go to Step 14. NO: Repair it. Then go to Step 14.