U0001

DTC U0001 CAN COMMUNICATION MALFUNCTION

Component Location:

GENERAL DESCRIPTION
The TCM can either receive data from the Engine Control Module or ABS control module, or it can send data to the ECM and ABSCM by using CAN communication. The CAN communication is one of the vehicle communications method, which is now widely used to transfer the vehicle data.

DTC DESCRIPTION
When the TCM cannot read the data from the ECM through the CAN-BUS line, the TCM sets this code. CAN-BUS circuit malfunctioning or ECM can be a possible cause of this DTC.

DTC Detecting Condition:

MONITOR SCANTOOL DATA
1. Connect Scantool to data link connector(DLC).
2. Engine "ON".
3. Monitor the "CAN COMMUNICATION SERVICE DATA (ENGINE RPM, VEHICLE SPEED SENSOR, THROTTLE P. SENSOR)" parameters on the Scantool.
4. Compare it with reference data as below.





5. Does "CAN BUS LINE DATA" follow the reference data?

YES
^ Fault is intermittent caused by poor contact in the sensor's and/or TCM(PCM)'s connector or was repaired and TCM(PCM) memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure.

NO
^ Go to "Terminal & Connector Inspection" procedure.

TERMINAL & CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?

YES
^ Repair as necessary and go to "Verification of vehicle Repair" procedure.

NO
^ Go to "Signal circuit inspection" procedure.

SIGNAL CIRCUIT INSPECTION
1. Ignition "ON" & Engine "OFF".
2. Disconnect the "PCM CM" connector.
3. Measure resistance between terminal "77" and "78" of the "PCM CM" harness connector.

C301:

4. Is measured resistance within specifications?

YES
^ Substitute with a known-good PCM CM and check for proper operation. If the problem is corrected, replace PCM CM as necessary and then go to "Verification of Vehicle Repair" procedure.

NO
^ Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration or damage of ECM.and then Repair or replace Resistance for CAN communication as necessary and go to "Verification of Vehicle Repair" procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.

1. Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Using a Scantool, Clear DTC.
3. Operate the vehicle within DTC Enable conditions in General information.
4. Are any DTCs present?

YES
^ Go to the applicable troubleshooting procedure.

NO
^ System performing to specification at this time.