Diagnostic Item 8
DIAGNOSTIC ITEM 8: Diagnose when the scan tool cannot receive the data sent by ABS-ECU [vehicles with ABS (Except vehicles with 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.
CAN-C Communication Circuit:
CAN-C Communication Circuit (Part 1):
CAN-C Communication Circuit (Part 2):
FUNCTION
If the scan tool MB991958 cannot communicate with the ABS-ECU [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU [vehicles with ASC], this diagnosis result will be set.
TROUBLE JUDGEMENT CONDITIONS
If a communication flag is not set for the ABS-ECU [vehicles with ABS (Except vehicles with 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 with ABS (Except vehicles with ASC)] or ASC-ECU connector [vehicles with ASC] improperly connected]
- Malfunction of the wiring harness [open circuit between the ABS-ECU connector [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU connector [vehicles with ASC] and the joint connector (CAN3), power supply circuit to the ABS-ECU [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU (vehicles with ASC)]
- Malfunction of the ABS-ECU [vehicles with ABS (Except vehicles with 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 with ABS (Except vehicles with 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.
Q: Are joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU connector A-51 [vehicles with AS] 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 with ABS (Except vehicles with ASC)] or ASC-ECU connector A-51 [vehicles with ASC] for open circuit.
CAUTION: Strictly observe the specified wiring harness repair procedure.
1. Disconnect joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles with ABS (Except vehicles with 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 6) and ABS-ECU connector A-03 (terminal 4) [vehicles with ABS (Except vehicles with ASC)]
OK: Continuity exists (2 ohms or less)
3. Check the wiring harness between joint connector (CAN3) C-124 (terminal 6) and ASC-ECU connector A-51 (terminal 12) [vehicles with ASC]
OK: Continuity exists (2 ohms or less)
4. Check the wiring harness between joint connector (CAN3) C-124 (terminal 19) and ABS-ECU connector A-03 (terminal 6) [vehicles with ABS (Except vehicles with ASC)]
OK: Continuity exists (2 ohms or less)
5. Check the wiring harness between joint connector (CAN3) C-124 (terminal 19) and 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 ASC-ECU connector A-05 in good condition?
YES : Check the power supply circuit of the ABS-ECU [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU [vehicles with ASC]. Refer to Troubleshooting [vehicles with ABS (Except vehicles with ASC)] Inspection Procedure 8: ABS-ECU Power Supply Circuit System or Troubleshooting [vehicles with ASC]. Inspection Procedure 12: ASC-ECU Power Supply Circuit System
NO : Repair the wiring harness between joint connector (CAN3) C-124 and ABS-ECU connector A-03 [vehicles with ABS (Except vehicles with ASC)] or ASC-ECU connector A-51 [vehicles with ASC].