Diagnostics Item 9

DIAGNOSTIC ITEM 9: Diagnose when the scan tool cannot receive the data sent by ABS-ECU [vehicles without ASC] or ASC-ECU [vehicles with ASC].

CAUTION:
When servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do so, a component connected to the CAN bus line may be damaged.






















FUNCTION

If the scan tool MB991958 cannot communicate with the ABS-ECU [vehicles without ASC]
or ASC-ECU [vehicles with ASC], this diagnosis result will be set.

TROUBLE JUDGMENT CONDITIONS

If a communication flag is not set for the ABS-ECU [vehicles without ASC] or ASC-ECU [vehicles with ASC], the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS

- Malfunction of the connector [joint connector (CAN3) or ABS-ECU connector [vehicles without ASC] or ASC-ECU connector [vehicles with ASC] improperly connected]

- Malfunction of the wiring harness [open circuit between the ABS-ECU connector [vehicles without ASC] or ASC-ECU connector [vehicles with ASC] and the joint connector (CAN3), power supply circuit to the ABS-ECU [vehicles without ASC] or ASC-ECU [vehicles with ASC]]

- Malfunction of the ABS-ECU [vehicles without ASC] or ASC-ECU [vehicles with ASC]

DIAGNOSIS

Required Special Tools:

- MB991223: Harness Set

- MB992006: Extra Fine Probe

STEP 1. Check joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC] for loose, corroded or damaged terminals, or terminals pushed back in the connector.

CAUTION:
The strand end of the twisted wire should be within 10 cm (4 inches) from the connector. For details refer to Precautions When CAN Bus Line(s) are Repaired.

Q. Are joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC] in good condition?

YES Go to Step 2.
NO Repair the damaged parts.
STEP 2. Check the wiring harness between joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC] for open circuit.

CAUTION:
Strictly observe the specified wiring harness repair procedure.
For details refer to Precautions When CAN Bus Line(s) are Repaired.

(1)Disconnect joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC], and check the wiring harness.









(2)Check the wiring harness between joint connector (CAN3) C-124 (terminal 9) and ABS-ECU connector A-03 (terminal 4) [vehicles without ASC] or ASC-ECU connector A-51 (terminal 12) [vehicles with ASC]
OK: Continuity exists (2 ohms or less)










(3)Check the wiring harness between joint connector (CAN3) C-124 (terminal 20) and ABS-ECU connector A-03 (terminal 6) [vehicles without ASC] or ASC-ECU connector A-51 (terminal 13) [vehicles with ASC]
OK: Continuity exists (2 ohms or less)

Q. Is the wiring harness between joint connector (CAN3) C-127 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC] in good condition?

YES Check the power supply circuit of the ABS-ECU [vehicles without ASC] or ASC-ECU [vehicles without ASC]. Inspection Procedure 8 [vehicles without ASC] or Troubleshooting Inspection Procedure 12 [vehicles with ASC].

NO Repair the wiring harness between joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles without ASC] or ASC-ECU connector A-51 [vehicles with ASC].