1: Communication W/Scan Tool Is Not Possible (ABS)

DATA LINK CONNECTOR CIRCUIT

















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 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 the 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 the terminal 4 and ground.
- Voltage should be approximately 12 volts (battery positive voltage.)
If not approximately 12 volts, go to Step 2.
If approximately 12 volts, go to Step 3.





STEP 2. Check the harness wire between ignition switch (IG2) and ABS-ECU connector. A-03 is damaged, repair it. Then go to Step 5.








NOTE: After inspecting intermediate connector C-12, C-73 or C-77 inspect the wire. If intermediate connector C-12, C-73 or C-77 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step. 5.








STEP 3. Check the harness wire between ABS-ECU connector A-03 and data link connector C-23.
If any harness wire between ABS-ECU connector A-03 and data link connector C-23 is damaged, repair it.
Then go to Step 5.
If the harness wire is not damaged, go to Step 4.








NOTE: After inspecting intermediate connector C- 12 or C-57 inspect the wire. If intermediate connector C- 12 or C-57 is damaged, repair or replace it. If the connector has been repaired or replaced, go to Step 5.





STEP 4. Check the harness wire between ABS-ECU connector A-03 and ground.
If any harness wire between ABS-ECU connector A-03 and ground is damaged, repair it. Then go to Step 5.
If the harness wire is not damaged, go to Step 5.
STEP 5. Check symptoms
Confirm that the intermediate connectors, the harness wires, and the hydraulic unit (integrated with ABS-ECU) are normal.