Inspection Procedure 7
Auto-cruise Control Indicator Light Drive Circuit:
Connectors:
CIRCUIT OPERATION
The power for the auto-cruise indicator in the combination meter is supplied from the ignition switch (IG1).
When the auto-cruise control system is operating, the transistor inside the auto-cruise control-ECU illuminates the auto-cruise indicator through ECU terminal number 15.
TECHNICAL DESCRIPTION (COMMENT)
The cause is probably the malfunction of the indicator bulb or the malfunction of the connector or harness.
TROUBLESHOOTING HINTS
- Malfunction of the indicator bulb.
- Damaged harness or connector.
- Malfunction of the auto-cruise control-ECU.
DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set
STEP 1.Check the auto-cruise control indicator bulb.
1. Remove the combination meter.
Refer to Combination Meter Assembly and Vehicle Speed Sensor.
2. Check the auto-cruise control indicator bulb.
Q: Is the bulb blown?
YES: Replace the bulb.
Then check that the malfunction is eliminated.
NO: Go to Step 2.
STEP 2.Check the output circuit voltage at auto-cruise control-ECU connector C-35 by backprobing.
1. Do not disconnect auto-cruise control-ECU connector C-35.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 15 and ground by backprobing.
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage approximately battery positive voltage?
YES: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU. Then check that the malfunction is eliminated.
NO: Go to Step 3.
STEP 3.Check the output circuit voltage at junction block connector D-06 by backprobing.
1. Do not disconnect junction block connector D-06.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 8 and ground by backprobing.
4. Turn the ignition switch to "LOCK" (OFF) position.
Q: Is the voltage approximately battery positive voltage?
YES: Go to Step 5.
NO: Go to Step 4.
STEP 4.Check junction block connector D-08.
Q: Is the connector damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Replace the junction block.
Then check that the malfunction is eliminated.
STEP 5.Check combination meter connector C-04 and C-05.
Q: Is any connector damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Go to Step 6.
STEP 6.Check the harness wire between combination meter connector C-04 and junction block connector D-06.
Q: Is any harness wire between combination meter connector C-04 and junction block connector D-06 damaged?
YES: Repair the harness wire and then check that the malfunction is eliminated.
NO: Go to Step 7.
STEP 7.Check the combination meter.
1. Remove the combination meter and measure at the combination meter side. (Refer to Combination Meter Assembly and Vehicle Speed Sensor.)
2. Measure the continuity between terminal 24 at conductor C-04 and terminal 8 at conductor C-05.
Q: Is the continuity less than 2 Ohms?
YES: Go to Step 8.
NO: Replace the combination meter.
Refer to Combination Meter Assembly and Vehicle Speed Sensor.
Then check that the malfunction is eliminated.
STEP 8.Check auto-cruise control-ECU connector C-35.
Q: Is the connector damaged?
YES: Repair or replace connector.
Refer to Harness Connector Inspection.
Then check that the malfunction is eliminated.
NO: Go to Step 9.
STEP 9.Check the harness wire between combination meter connector C-05 and auto-cruise control-ECU connector C-35.
Q: Is any harness wire between combination meter connector C-05 and auto-cruise control-ECU connector C-35 damaged?
YES: Repair the harness wire and then check that the malfunction is eliminated.
NO: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU.
Then check that the malfunction is eliminated.