Diagnostic Item 6

DIAGNOSTIC ITEM 6: Diagnose when the scan tool cannot receive the data sent by AWD-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.

CAN Communication Circuit Part 1:

CAN Communication Circuit Part 2:

FUNCTION
If the scan tool MB991958 cannot communicate with the AWD-ECU, this diagnosis result will be set.

TROUBLE JUDGEMENT CONDITIONS
If a communication flag is not set for the AWD-ECU, the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS
- Malfunction of the connector [joint connector (CAN2) or AWD-ECU connector improperly connected]
- Malfunction of the wiring harness [open circuit between the AWD-ECU and the joint connector (CAN2), power supply circuit to the AWD-ECU]
- Malfunction of the AWD-ECU

DIAGNOSIS

Required Special Tools:
- MB991223: Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check joint connector (CAN2) C-04, AWD-ECU connector C-128 and intermediate connector C-31 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.

Q: Are joint connector (CAN2) C-04, AWD-ECU connector C-128 and intermediate connector C-31 in good condition?

YES: Go to Step 2.

NO: Repair the damaged parts.

STEP 2. Check the wiring harness between joint connector (CAN2) C-04 and AWD-ECU connector C-128.

CAUTION: Strictly observe the specified wiring harness repair procedure.

1. Disconnect joint connector (CAN2) C-04 and AWD-ECU connector C-301, and check the wiring harness.
2. Check the wiring harness between joint connector (CAN2) C-04 (terminal No.5) and AWD-ECU connector C-128 (terminal No.5)
3. Check the wiring harness between joint connector (CAN2) C-04 (terminal No.16) and AWD-ECU connector C-128 (terminal No.13)

Q: Is the wiring harness between joint connector (CAN2) C-04 and AWD-ECU connector C-128 in good condition?

YES: Check the power supply circuit of the AWD-ECU. Refer to Electronic Control, Multiselect AWD Diagnosis.

NO: Repair the wiring harness between joint connector (CAN2) C-04 and AWD-ECU connector C-128.