Inspection Procedure A-1

Scan tool MB991502 communication Is not possible.

ETACS-ECU Power Supply And Scan Tool Communication Circuit:

Connectors:

CIRCUIT OPERATION
The ETACS-ECU receives a diagnostic trouble code and 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:Scantool(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 Computers/Testing/Trouble Code Diagnostic Procedures.
NO (can not communicate with SWS 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 P-1.







STEP 3. Check data link connector C-26 and ETACS-ECU connector C-313 for damage.

Q: Are data link connector C-26 and ETACS-ECU connector C-313 in good condition?

YES: Go to Step 4.
NO: Repair or replace them. Refer to Harness Connector Inspection. Scan tool MB991502 should communicate with the SWS.







STEP 4. Check the harness wires between data link connector C-26 and ETACS-ECU connector C-313.

NOTE: After checking joint connector C-140, check The wires. If joint connector C-140 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Q: Are the harness wires between data link connector C-26 and ETACS-ECU connector C-313 in good condition?

YES: Go to Step 5.
NO: Repair them. Scan tool MB991502 should communicate with the SWS.

STEP 5. Check the ETACS-ECU ground circuit at the ETACS-ECU connector C-311.
1. Disconnect the ETACS-ECU connector C-311 and measure at the junction block side.




2. Measure the resistance between terminal 1 and ground.

Q: Is the resistance less than 2 ohm?

YES: Replace the ETACS-ECU. Scan tool MB991502 should communicate with the SWS.
NO: Go to Step 6.




STEP 6. Check the ETACS-ECU connector C-313 for damage.

Q: Is ETACS-ECU connector C-313 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 SWS.







STEP 7. Check the harness wires between ETACS-ECU connector C-313 and ground.

NOTE: After checking junction block connector C-301, check the wires. If junction block connector C-301 is damaged, repair or replace it. Refer to Harness Connector Inspection.

Q: Are the harness wires between ETACS-ECU connector C-301 and ground in good condition?

YES: There is no action to be taken.
NO: Repair them. Scan tool MB991502 should communicate with the SWS.