Inspection Procedure 1

Auto-cruise Control-ECU Supply, Ground And Data Link Circuit:

Connectors:

CIRCUIT OPERATION
Power of the auto-cruise control-ECU is transmitted from the ignition switch (IG1) to the auto-cruise control-ECU through multi-purpose fuse 11 in the junction block.

TECHNICAL DESCRIPTION (COMMENT)
The cause is probably a malfunction of the auto-cruise control-ECU power supply circuit or the auto-cruise control-ECU ground circuit.

TROUBLESHOOTING HINTS
- Damaged harness or connector.
- Malfunction of the auto-cruise control-ECU.

DIAGNOSIS
Required Special Tool:
- MB991223: Harness Set




STEP 1.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 6 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 2.




STEP 2.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 3.







STEP 3.Check junction block connector D-08 and D-06.

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 4.




STEP 4.Check the harness wire between ignition switch and auto-cruise control-ECU connector C-35.

Q: Is any harness wire between ignition switch 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.




STEP 5.Check the ground 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 14 and ground by backprobing.
4. Turn the ignition switch to "LOCK" (OFF) position.

Q: Is the voltage approximately 0.5 volts or less?

YES: Go to Step 8.

NO: Go to Step 6.




STEP 6.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 7.




STEP 7.Check the harness wire between auto-cruise control-ECU connector C-35 and ground.

Q: Is any harness wire between auto-cruise control-ECU connector C-35 and ground 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.




STEP 8.Check the output circuit voltage at data link connector C-69.
1. Turn the ignition switch to "ON" position.
2. Measure the voltage between terminal 13 and ground.
3. Turn the ignition switch to "LOCK" (OFF) position.

Q: Is the voltage approximately 4 volts or more?

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 9.




STEP 9.Check data link connector C-69.

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 10.




STEP 10.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 11 and ground by backprobing.
4. Turn the ignition switch to "LOCK" (OFF) position.

Q: Is the voltage approximately 4 volts or more?

YES: Go to Step 11.

NO: Go to Step 12.







STEP 11.Check the harness wire between auto-cruise control-ECU connector C-35 and data link connector C-69.

Q: Is any harness wire between auto-cruise control-ECU connector C-35 and data link connector C-69 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.




STEP 12.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: Check that the malfunction is eliminated.
If the malfunction is eliminated, replace the auto-cruise control-ECU.
Then check that the malfunction is eliminated.