As vehicles electronically controlled, various control unit is applied to vehicle and several units are controlled based on the signals from the sensors. Therefore sharing signals of sensors and information is required. To meet this requirement, CAN communication type, which is insensible to external noises and whose communication speed is fast, is applied to power train control.
Sharing signals from RPM, APS, gear shifting, torque reduction in ESP, ABS and various modules, addtive control is performed.
If it is impossible to communicate through internal or external CAN line over 500ms, PCM sets DTC U0001.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● CAN communication status check | ● Poor connection ● Open/Short ● PCM |
Enable Conditions | ● Battery voltage ＞ 10.7V ● Ignition on, no start phase | |
Threshold Value | ● Bus-Off time on external CAN ＞ 500ms ● Bus-Off time on internal CAN ＞ 500ms | |
Diagnostic Time | ● Continuous | |
MIL ON Condition | ● 5 sec |
Connect scantool to Data Link Connector(DLC).
Warm up the engine to normal operating temperature.
Monitor the "CAN" parameters on the scantool.
Check the value of current data displayed normally.
Check "Transaxle Range Switch" and "Torque Reqired from TCU" parameters among ECU's current data. (AT vehicle only)
Check "TPS", "RPM", and "Idle Status" parameters among TCU's current data. (AT vehicle only)
Check "RPM" and "TPS" parameters among ABS's current data. (ABS or ESP vehicle only)
Are the parameters displayed correctly?
▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or wasrepaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poorconnection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.
▶ Go to "Terminal and connector inspection" procedure.
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.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and go to "Verification of vehicle Repair" procedure.
▶ Go to "CAN communication circuit inspection" procedure.
Check CAN BUS Short to Ground.
Key "OFF".
Disconnect PCM connector.
Measure the resistance between terminal 12/27 of PCM harness connector and chassis ground. [A/T]
Measure the resistance between terminal 62/84 of PCM(ECM) harness connector and chassis ground. [M/T]
Specification : Infinite
Is the measured resistance within specification?
▶ Go to "CAN BUS Terminus Resistance Check(Harness side)" procedure.
▶ Repair Short in signal circuit and then go to "Verification of vehicle Repair" procedure.
CAN BUS Terminus Resistance Check(Harness side)
Key "OFF".
Disconnect PCM connector.
Measure the resistance between terminal 12 and 27 of PCM harness connnector. [A/T]
Measure the resistance between terminal 62 and 84 of ECM harness connnector. [M/T]
Specification : 120Ω ± 10Ω
Is the measured resistance within specification?
▶ Go to "Component Inspection" procedure.
▶ In case the measured resistance is around 1.0Ω : Repair Short in signal circuit and then go to "Verification of vehicle Repair" procedure.
▶ In case the measured resistance is Infinite : Repair Open in signal circuit and then go to "Verification of vehicle Repair" procedure.
CAN BUS Terminus Resistance Check (Component side)
Key "OFF".
Disconnect PCM connector.
Measure the resistance between terminal 12 and 27 of PCM connnector. [A/T]
Measure the resistance between terminal 62 and 84 of ECM connnector. [M/T]
(Component side)
Specification : 120Ω ± 10Ω
Is the measured resistance within specification?
▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or wasrepaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poorconnection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of vehicle Repair" procedure.
▶ Substitute with a known - good ECM and check for proper operation.
▶ If the problem is corrected, replace ECM and go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete".
If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
Read "DTC Status" parameter.
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC.
▶ Go to the applicable troubleshooting procedure.
