Inspection Procedure 5

Scan Tool MB991502 Communication is not Possible.

ETACS-ECU Power Supply And Scan Tool Communication Circuit:

Connectors:

CIRCUIT OPERATION
The ETACS-ECU receives switch signals from the data link connector.

TECHNICAL DESCRIPTION (COMMENT)
The harness wires between the ETACS-ECU power supply line or the ETACS-ECU and the data link connector may be defective.

TROUBLESHOOTING HINTS
- Malfunction of the ETACS-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check the communication with other Systems.

Q: Can the scan tool communicate with no systems?

YES: Refer to Diagnosis.

NO (can not communicate with switch signal only: Go to Step 2.

STEP 2. Check the ignition switch positions.

Q: Can scan tool MB991502 communicate with the ETACS-ECU with the ignition switch at any position other than "ON"?

YES: Go to Step 3.

NO: Check the ETACS-ECU battery circuits. Refer to Inspection Procedure 8.







STEP 3. Check data link connector C-69 and ETACS-ECU connector D-27 for damage.

Q: Are data link connector C-69 and ETACS-ECU connector D-27 in good condition?

YES: Go to Step 4.

NO: Repair or replace them. Refer to Harness Connector Inspection. Scan tool MB991502 should communicate with switch signals.










STEP 4. Check the harness wires between data link connector C-69 and ETACS-ECU connector D-27.

NOTE: After checking joint connector C-10, check the wires. If joint connector C-10 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Q: Are the harness wires between data link connector C-69 and ETACS-ECU connector D-27 in good condition?

YES: Go to Step 5.

NO: Repair them. Scan tool MB991502 should communicate with the switch signals.




STEP 5. Check the ETACS-ECU ground circuit at the ETACS-ECU connector D-11.
1. Disconnect the ETACS-ECU connector D-11 and measure at the harness side.
2. Measure me resistance between terminal 10 and ground.

Q: Is the resistance less than two Ohms?

YES: Replace the ETACS-ECU. Scan tool MB991502 should communicate with the switch signals.

NO: Go to Step 6.




STEP 6. Check the ETACS-ECU connector D-11 for damage.

Q: Is ETACS-ECU connector D-11 in good condition?

YES: Go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. Scan tool MB991502 should communicate with the switch signals.




STEP 7. Check the harness wires between ETACS-ECU connector D-11 and ground.

NOTE: After checking junction block connector D-13, check the wires. If junction block connector D-13 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Q: Are the harness wires between ETACS-ECU connector D-11 and ground in good condition?

YES: Go to Step 8.

NO: Repair them. Scan tool MB991502 should communicate with the switch signals.

STEP 8. Recheck for malfunction.

Q: Is a malfunction eliminated?

YES: This diagnosis is complete. (If no malfunctions are not found in all steps, an intermittent malfunction is suspected. Refer to How to Use Troubleshooting/Inspection Service Point.)

NO: Go to step 1.