Trouble Diagnosis
TROUBLE DIAGNOSISCondition of Error Detection
"U1000" or "U1001" is indicated on SELF-DIAG RESULTS on CONSULT-II if CAN communication signal is not transmitted or received between units for 2 seconds or more.
CAN COMMUNICATION SYSTEM ERROR
- CAN communication line open (CAN-H, CAN-L, or both)
- CAN communication line short (ground, between CAN communication lines, other harnesses)
- Error of CAN communication control circuit of the unit connected to CAN communication line
WHEN INDICATED "U1000" OR "U1001" IS INDICATED EVEN THOUGH CAN COMMUNICATION SYSTEM IS NORMAL
- CONSULT-II CONVERTER not connected: Error may be detected by the self-diagnosis when not using CONSULT-II CONVERTER (Depending on the control unit which carries out CAN communication).
- Removal/installation of parts: Error may be detected when removing and installing CAN communication unit and related parts while turning the ignition switch ON. (A DTC except for CAN communication may be detected.)
- Fuse blown out (removed): CAN communication of the unit may cease.
- Voltage drop: Error may be detected if voltage drops due to discharged battery when turning the ignition switch ON (Depending on the control unit which carries out CAN communication).
- Error may be detected if the power supply circuit of the control unit, which carries out CAN communication, malfunctions (Depending on the control unit which carries out CAN communication).
- Error may be detected if reprogramming is not completed normally.
NOTE: CAN communication system is normal if "U1000" or "U1001" is indicated on SELF-DIAG RESULTS of CONSULT-II under the above conditions. Erase the memory of the self-diagnosis of each unit.
Symptom When Error Occurs in CAN Communication System
In CAN communication system, multiple units mutually transmit and receive signals. Each unit cannot transmit and receive signals if any error occurs on CAN communication line. Under this condition, multiple control units related to the root cause malfunction or go into fail-safe mode.
ERROR EXAMPLE
NOTE:
- Each vehicle differs in symptom of each unit under fail-safe mode and CAN communication line wiring.
- Refer to LAN-41, "Abbreviation List" for the unit abbreviation. Abbreviation List
Example: TCM branch line open circuit
Example: Data link connector branch line open circuit
NOTE:
- When data link connector branch line is open, transmission and reception of CAN communication signals is not affected. Therefore, no symptoms occur. However, be sure to repair malfunctioning circuit.
- When data link connector branch line is open, the screen-display of the CONSULT-II SELECT SYSTEM screen may be the same as when the CAN communication line has short-circuit. However, symptoms differ depending on the case. See below chart for the differences.
Example: Main Line Between Data Link Connector and ABS Actuator and Electric Unit (Control Unit) Open Circuit
Example: CAN-H, CAN-L Harness Short Circuit
CAN Diagnostic Support Monitor
CONSULT-II and CAN diagnostic support monitor (on-board diagnosis function) are used for detecting root cause.
MONITOR ITEM (CONSULT-II)
MONITOR ITEM (ON-BOARD DIAGNOSIS)
NOTE: For some models, CAN communication diagnosis result is received from the vehicle monitor. (CONSULT-II is not available.)
Example: Vehicle Display
How to Use CAN Communication Signal Chart