Diagnostic Item 8

DIAGNOSTIC ITEM 8: Diagnose when the scan tool cannot receive the data sent by ECM.

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 2):

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

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

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

DIAGNOSIS

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

STEP 1. Check joint connector (CAN3) C-124 and ECM connector B-109 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 (CAN3) C-124 and ECM connector B-109 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 ECM connector B-109.

CAUTION: Strictly observe the specified wiring harness repair procedure.

1. Disconnect joint connector (CAN3) C-124 and ECM connector B-109, and check the wiring harness.
2. Check the wiring harness between joint connector (CAN3) C-124 (terminal 4) and ECM connector B-109 (terminal 90)
3. Check the wiring harness between joint connector (CAN3) C-124 (terminal 15) and ECM connector B-109 (terminal 91)

Q: Is the wiring harness between joint connector (CAN3) C-124 and ECM connector B-109 in good condition?

YES : Check the power supply circuit of the ECM. Refer to MFI, Troubleshooting.

NO : Repair the wiring harness between joint connector (CAN3) C-124 and ECM connector B-109.