Inspection Procedure 15

Inspection procedure 15: Acceleration shock

COMMENT
- There may be an ignition leak accompanying the increase in the spark plug demand voltage during acceleration.

TROUBLESHOOTING HINTS (The most likely causes for this case:)
- Malfunction of the ignition system.
- Malfunction of the TC-SST system.
- Malfunction of the ECM.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

NOTE: To protect the TC-SST, the TC-SST-ECU outputs, into the ECM, the request signal to reduce the engine torque according to the operation condition. Based on the signal, the ECM closes the throttle valve, retards the ignition or carries out fuel cut. At that time, the engine output seems to temporarily reduce, but there is no malfunction.

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

Q: Is any DTC set?

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

NO : Go to Step 2.

STEP 2. Using scan tool MB991958, read the diagnostic trouble code (DTC).

NOTE: When the TC-SST has a malfunction, the TC-SST-ECU might output the request signal of reducing the engine torque in order to protect the TC-SST.

1. Turn the ignition switch to the "ON" position.
2. Read the TC-SST-DTC.
3. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the TC-SST-DTC set?

YES : Refer to Diagnosis [TC-SST] - Diagnostic Trouble Code Chart. Diagnostic Trouble Code Descriptions

NO : Go to Step 3.

STEP 3. Check the spark plugs.

Q: Are there any abnormalities?

YES : Replace the spark plug. Then confirm that the malfunction symptom is eliminated.

NO : Go to Step 4.

STEP 4. Check the ignition coil.

Q: Are there any abnormalities?

YES : Replace the ignition coil. Then confirm that the malfunction symptom is eliminated.

NO : Check for occurrence of ignition leak. Then confirm that the malfunction symptom is eliminated.