Inspection Procedure 1

INSPECTION PROCEDURE 1: Communication between the Scan Tool and the ABS-ECU is not

CIRCUIT OPERATION
^ The diagnostic output is made from the ABS-ECU (terminal 11) 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 12) will go into 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 case)
^ Blown fuse
^ Damaged wiring harness and 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-02.





1) Disconnect connector A-02 and measure at the harness side.
2) Start the engine.
3) Measure the voltage between terminal 15 and ground.

Q: Is battery positive voltage (approximately 12 volts) present?
YES: Go to Step 3.
NO: Go to Step 2.

STEP 2. Check the harness wire between Ignition Switch (IGS) corrector C-202 terminal 4 and ABS-ECU connector A-02 terminal 15.











NOTE. After inspecting intermediate connectors C-212, C-311, and C-312, inspect the Yore; If intermediate connector

Q: Is any harness wire between ignition switch (IG2) connector C-202 terminal 4 and ABS-ECU connector A02 terminal 15 damaged?
YES: Repair them and go to Step 5.
NO: Go to Step 3.

STEP 3. Check the harness wire between ABS-ECU II connector A-02 terminal 11 and data link connector C-26 terminal 7 or ABS-ECU connector A-02 terminal 12 and datalink connector C-26 terminal 1.

NOTE: After inspecting intermediate connectors C-140 and C-12. inspect the wire. If intermediate connector C-140 or C-212 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 4.

Q: Is any harness wire between ABS-ECU connector A-02 terminal 11 and data link connector C-26 terminal 7 or ABS-ECU connector A-02 terminal 12 and data link connector C-26 terminal 1 damaged?
YES: Repair them and go to Step 5.
NO: Go to Step 4.

STEP 4. Check the harness wires between ABS-ECU connector A-02 terminal 19 and ground.

Q: Are any harness wires between ABS-ECU connector A02terminal 19 and ground damaged?
YES: Repair them and then go to Step 5.
NO: Go to Step 5.

STEP 5. Check symptom.
Q: Does the scan tool communicate with the ABS system?
YES: The procedure is complete.
NO: Return to Step 1.