Inspection Procedure 5
Auto-cruise Control Cannot Be Set.TECHNICAL DESCRIPTION (COMMENT)
The fail-safe function is probably cancelling auto-cruise control. In this case, scan tool MB991502 can be used to retest the system in each system by checking the diagnostic trouble codes. The scan tool can also be used to check if the circuits of each input switch are normal or not by checking the input switch codes.
TROUBLESHOOTING HINTS
- Malfunction of the auto-cruise control switch.
- Malfunction of the auto-cruise control-ECU.
DIAGNOSIS
Required Special Tools:
- MB991502: Scan Tool (MUT-II)
- MB991223: Harness Set
STEP 1. Can the auto-cruise control-ECU communicate with scan tool MB991502?
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Using scan tool MB991502.
2. Connect scan tool MB991502 to the data link connector.
3. Turn the ignition switch to the "ON" position.
4. Select "Auto-cruise control system".
5. Turn the ignition switch to the "LOCK" (OFF) position.
6. Disconnect scan tool MB991502.
Q: Can the auto-cruise control-ECU communicate with the scan tool?
YES: Go to Step 2.
NO: Inspect each trouble symptom. (Refer to Inspection Procedure number 1).
STEP 2. Using scan tool MB991502, check the any DTC set.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Using scan tool MB991502.
2. Connect scan tool MB991502 to the data link connector.
3. Turn the ignition switch to the "ON" position.
4. Read the DTC.
5. Turn the ignition switch to the "LOCK" (OFF) position.
6. Disconnect scan tool MB991502.
Q: Is any DTC set?
YES: DTC 11, 12, 14, 15, 16 or 17 is set (Refer to Diagnostic Trouble Code Chart).
NO: Go to Step 3.
STEP 3. Using scan tool MB991502, check data list.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Using scan tool MB991502.
2. Connect scan tool MB991502 to the data link connector.
3. Check the following items in the data list. (Refer to Data List Reference Table).
- Item 04: Auto-cruise control CANCEL switch.
- Item 05: Stoplight switch.
- Item 14: Park/neutral position switch.
4. Turn the ignition switch to the "ON" position.
5. Disconnect scan tool MB991502.
Q: Does the checks above meet the specifications?
YES: Check that the malfunction is eliminated. If the malfunction is eliminated, it can be assumed that this malfunction is intermittent. If the malfunction is not eliminated, replace the auto-cruise control-ECU.
NO: Follow the diagnostic trouble code procedures and the symptom procedures below.
- Item 04: Refer to Diagnostic Trouble Code Procedures number 15.
- Item 05: Refer to Symptom Procedures number 2.
- Item 14: Refer to Symptom Procedures number 3.