1: Communication W/ Scan Tool Is Not Possible

INSPECTION PROCEDURE 1: Communication With Scan Tool is not Possible. (Communication With TCL Only is not Possible.)





Part 1 of 2





Part 2 of 2

CIRCUIT OPERATION
^ The diagnostic output is made from the ABS-ECU (terminal 7) to the diagnostic output terminal (terminal 7) of the data link connector.
^ When the data link connector's diagnostic test mode control terminal (terminal 1) is grounded, the ABS-ECU (terminal 14) will switch to the diagnostic mode.

TECHNICAL DESCRIPTION (COMMENT)
When communication with the scan tool is not possible, the cause is probably an open circuit in the ABS-ECU power circuit or an open circuit in the diagnostic output circuit.

TROUBLESHOOTING HINTS
The most likely causes for this condition:
^ Blown fuse
^ Damaged wiring harness or connector
^ Malfunction of the hydraulic unit (Integrated with ABS-ECU)

DIAGNOSIS

Required Special Tool:
^ MB991223: Harness Set





STEP 1. Check the power supply circuit at ABS-ECU connector A-03.
1. Disconnect connector A-03 and measure at the harness side.
2. Start the engine.
3. Measure the voltage between terminal 4 and ground.
Q: Is the voltage approximately 12 volts?
YES: Go to Step 3.
NO: Go to Step 2.











STEP 2. Check the harness wire between ignition switch (IG2) and ABS-ECU connector A-03.

NOTE: After inspecting intermediate connectors C-12, C-84 and C-87, inspect the wire. If intermediate connector C-12, C-84 or C-87 is damaged, repair or replace it. If the connector has been repaired, go to Step 5.

Q: Are any harness wires between ABS-ECU connector A-03 and ignition switch (IG2) damaged?
YES: Repair them and then go to Step 5.
NO: Go to Step 5.














STEP 3. Check the harness wires between ABS-ECU connector A-03 and data link connector C-23.

NOTE: Alter inspecting intermediate connectors C-12 and C-57, inspect the wires. If intermediate connector C-12 or C-57 is damaged, repair or replace it. If the connector has been repaired, go to Step 5.

Q: Are any harness wires between ABS-ECU connector A-03 and data link connector C-23 damaged?
YES: Repair them and then go to Step 5.
NO: Go to Step 4.





STEP 4. Check the harness wires between ABS-ECU connector A-03 and ground.
Q: Are any harness wires between ABS-ECU connector A-03 and ground damaged?
YES: Repair them and then go to Step 5.
NO: Replace the ABS-ECU and then go to Step 5.

STEP 5. Check symptom.
Q: Does the scan tool will now communicate with the TCL system?
YES: This diagnosis is complete.
NO: Return to Step 1.