Diagnostic Item 21

DIAGNOSTIC ITEM 21: Diagnose When The Scan Tool Cannot Receive The Data Sent By CAN Box Unit.

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-B Communication Circuit (Part 1):

CAN-B Communication Circuit (Part 2):

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

TROUBLE JUDGMENT CONDITIONS
If a communication flag is not set for the CAN box unit, the ETACS-ECU determines that there is a failure.

TROUBLESHOOTING HINTS
- Malfunction of the connector [joint connector (CAN1), CAN box unit connector improperly connected]
- Malfunction of the wiring harness [open circuit between the CAN box unit connector and the joint connector (CAN1), power supply circuit to the CAN box unit]
- Malfunction of the CAN box unit

DIAGNOSIS

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

STEP 1. Check joint connector (CAN1) C-105, CAN box unit connector C-15 and intermediate connector C-108 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 (CAN1) C-105, CAN box unit connector C-15 and intermediate connector C-108 in good condition?

YES : Go to Step 2.

NO : Repair the damaged parts.

STEP 2. Check the wiring harness between joint connector (CAN1) C-105 and CAN box unit connector C-15 for open circuit.

CAUTION: Strictly observe the specified wiring harness repair procedure.

1. Disconnect joint connector (CAN1) C-105 and CAN box unit connector C-15, and check the wiring harness.







2. Check the wiring harness between joint connector (CAN1) C-105 (terminal 5) and CAN box unit connector C-15 (terminal 8)

OK: Continuity exists (2 ohms or less)







3. Check the wiring harness between joint connector (CAN1) C-105 (terminal 16) and CAN box unit connector C-15 (terminal 9)

OK: Continuity exists (2 ohms or less)

Q: Is the wiring harness between joint connector (CAN1) C-105 and CAN box unit connector C-15 in good condition?

YES : Check the power supply circuit of the CAN box unit. Refer to Diagnosis [MMCS]. Trouble Symptom Chart

NO : Repair the wiring harness between joint connector (CAN1) C-105 and CAN box unit connector C-15.