Diagnostics Item 9

DIAGNOSTIC ITEM 9: Diagnose when the scan tool cannot receive the data sent by ASC-ECU.

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 ASC-ECU, this diagnosis result will be set.

TROUBLE JUDGMENT CONDITIONS

If a communication flag is not set for the ASC-ECU, the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS

- Malfunction of the connector [joint connector (CAN3) or ASC-ECU connector improperly connected]
- Malfunction of the wiring harness [open circuit between the ASC-ECU and the joint connector (CAN3), power supply circuit to the ASC-ECU]
- Malfunction of the ASC-ECU

DIAGNOSIS

Required Special Tools:

- MB991223: Harness Set
- MB992006: Extra Fine Probe
- MB991997: ASC Check Harness

STEP 1. Check joint connector (CAN3) C-127 and ASC-ECU connector A-05 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-127 and ASC-ECU connector A-05 in good condition?

YES Go to Step 2.
NO Repair the damaged parts.
STEP 2. Check the wiring harness between joint connector (CAN3) C-127 and ASC-ECU connector A-05 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-127 and ASC-ECU connector A-05, and check the wiring harness.





(2)Check the wiring harness between joint connector (CAN3) C-127 (terminal 6) and ASC-ECU connector A-05 (terminal 12)
OK: Continuity exists (2ohms or less)






(3)Check the wiring harness between joint connector (CAN3) C-127 (terminal 19) and ASC-ECU connector A-05 (terminal 13)
OK: Continuity exists (2ohms or less)

Q. Is the wiring harness between joint connector (CAN3) C-127 and ASC-ECU connector A-05 in good condition?

YES Check the power supply circuit of the ASC-ECU. Inspection Procedure 11.

NO Repair the wiring harness between joint connector (CAN3) C-127 and ASC-ECU connector A-05.