Trouble Diagnosis

TROUBLE DIAGNOSIS

Condition of Error Detection
"U1000" or "U1001" is indicated on SELF-DIAG RESULTS on CONSULT-III 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 "U1000" OR "U1001" IS INDICATED EVEN THOUGH CAN COMMUNICATION SYSTEM IS NORMAL
- 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- III 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 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 are not affected. Therefore, no symptoms occur. However, be sure to repair malfunctioning circuit.
- When data link connector branch line is open, "ECU list" displayed on the CONSULT-III "CAN DIAG SUPPORT MNTR" 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









Self-Diagnosis

U1000-U1010:

CAN Diagnostic Support Monitor
CONSULT-III and CAN diagnostic support monitor (on-board diagnosis function) are used for detecting root cause.

MONITOR ITEM (CONSULT-III)

Example: CAN DIAG SUPPORT MNTR indication






MONITOR ITEM (ON-BOARD DIAGNOSIS)

NOTE:
- For some models, CAN communication diagnosis result is received from the vehicle monitor. (CONSULT-III is not available.)
- Refer to "Trouble Diagnosis" for the details. Trouble Diagnosis