STEP 1. Check harness connector A-25X at throttle actuator control motor relay for damage.
STEP 2. Check the throttle actuator control motor relay.
(1) Remove the throttle actuator control motor relay.
(2) Check for continuity between the throttle actuator control motor relay terminal No. 1 and No. 2.- There should be continuity.
(3) Use jumper wires to connect throttle actuator control motor relay terminal No. 2 to the positive battery terminal and terminal No. 1 to the negative battery terminal.
(4) Check for continuity between the throttle actuator control motor relay terminal No. 3 and No. 4 while connecting and disconnecting the jumper wire at the negative battery terminal.- Continuity (2 ohms or less). <Negative battery terminal connected>
- Should be open loop. <Negative battery terminal disconnected>
(5) Install the throttle actuator control motor relay.
Is the measured resistance normal?
Go to Step 3. Replace the throttle actuator control motor relay. Then go to Step 15.
STEP 3. Measure the power supply voltage at throttle actuator control motor relay harness side connector A-25X.
STEP 4. Measure the power supply voltage at throttle actuator control motor relay harness side connector A-25X.
(1) Disconnect the connector A-25X and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal No. 2 and ground.- Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 6. Go to Step 5.
STEP 5. Check harness connector A-37X at MFI relay for damage.
STEP 6. Check harness connector B-27 at ECM for damage.
STEP 7. Measure the power supply voltage at ECM harness side connector B-27.
(1) Disconnect the connector B-27 and measure at the harness side.
(2) Short-circuit the terminal No. 73 of the ECM harness connector to the ground.
(3) Measure the voltage between terminal No. 84 and ground.- Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 8. Repair harness wire between throttle actuator control motor relay connector A-25X (terminal No. 1) and ECM connector B-27 (terminal No. 84) because of open circuit or short circuit to ground. Then go to Step 15.
STEP 8. Measure the power supply voltage at ECM harness side connector B-27.
(1) Disconnect the connector B-27 and measure at the harness side.
(2) Short-circuit the terminals No. 73 and No. 84 of the ECM harness connector to the ground.
(3) Measure the voltage between terminal No. 72 and ground.- Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 12. Go to Step 9.
STEP 9. Check for open circuit and short circuit to ground between throttle actuator control motor relay connector A-25X (terminal No. 3) and ECM connector B-27 (terminal No. 72).
STEP 10. Check harness connector A-37X at MFI relay for damage.
STEP 11. Check for harness damage between MFI relay connector A-37X (terminal No. 2) and throttle actuator control motor relay connector A-25X (terminal No. 2).
STEP 12. Check for harness damage between battery and throttle actuator control motor relay connector A-25X (terminal No. 4).
STEP 13. Check for harness damage between throttle actuator control motor relay connector A-25X (terminal No. 3) and ECM connector B-27 (terminal No. 72).
STEP 14. 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.
Is DTC P0657 set?
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 15. It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
STEP 15. 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.
Is DTC P0657 set?
Retry the troubleshooting. The inspection is complete.