DIAGNOSIS Required Special Tools: • MB991958: Scan Tool (MUT-III Sub Assembly) MB991824: V.C.I MB991827: USB Cable MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 13: Intake Air Temperature Sensor.

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 to the data reading mode for item 13, Intake Air Temperature Sensor. • The intake air temperature and temperature shown with the scan tool should approximately match. (4) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the sensor operating properly? YES: It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points . NO: Go to Step 2.

STEP 2. Check connector A-01 at the intake air temperature sensor for damage.

Q: Is the connector in good condition? YES: Go to Step 3. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 3. Check the intake air temperature sensor.

(1) Disconnect the intake air temperature sensor connector A-01.

(2) Measure the resistance between intake air temperature sensor side connector terminal No. 5 and No. 6. • There should be continuity. (0.30 - 20 kΩ) Q: Is the measured resistance between 0.30 and 20 kΩ? YES: Go to Step 4. NO: Replace the volume airflow sensor. Then go to Step 11.

STEP 4. Measure the sensor supply voltage at intake air temperature sensor harness side connector A-01.

(1) Disconnect the connector A-01 and measure at the harness side. (2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal No. 6 and ground. • Voltage should be between 4.5 and 4.9 volts. (4) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage between 4.5 and 4.9 volts? YES: Go to Step 8. NO: Go to Step 5.

STEP 5. Measure the sensor supply voltage at PCM connector C-90 by backprobing.

(1) Do not disconnect the PCM connector C-90. (2) Disconnect the intake air temperature sensor connector A-01. (3) Turn the ignition switch to the "ON" position.

(4) Measure the voltage between terminal No. 64 and ground by backprobing. • Voltage should be between 4.5 and 4.9 volts. (5) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage between 4.5 and 4.9 volts? YES: Go to Step 6. NO: Go to Step 7.

STEP 6. Check connector C-90 at PCM for damage.

Q: Is the connector in good condition? YES: Repair harness wire between intake air temperature sensor connector A-01 (terminal No.6) and PCM connector C-90 (terminal No. 64) because of open circuit. Then go to Step 11. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 7. Check connector C-90 at PCM for damage.

Q: Is the connector in good condition? YES: Replace the PCM. Then go to Step 11. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 8. Check for continuity at intake air temperature sensor harness side connector A-01.

(1) Disconnect the connector A-01 and measure at the harness side. (2) Check for the continuity between terminal No. 5 and ground. • Should be less than 2 ohms. Q: Does continuity exist? YES: Replace the PCM. Then go to Step 11. NO: Go to Step 9.

STEP 9. Check connector C-90 at PCM for damage.

Q: Is the connector in good condition? YES: Go to Step 10. NO: Repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11.

STEP 10. Check for open circuit between intake air temperature sensor connector A-01 (terminal No.5) and PCM connector C-90 (terminal No.57).

NOTE: Check harness after checking intermediate connector C-71. If intermediate connector is damaged, repair or replace it. Refer to GROUP 00E, Harness Connector Inspection . Then go to Step 11. Q: Is the harness wire in good condition? YES: Replace the PCM. Then go to Step 11. NO: Repair it. Then go to Step 11.