Component Location
General Description
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.
DTC Description
If it is impossible to communicate through internal or external CAN line over 500ms, ECM sets DTC U0001.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | CAN communication status check
| Poor connection Open/Short |
Enable Conditions | IG ON
|
Threshold Value | CAN BUS error
|
Diagnostic Time | Continuous
|
MIL ON Condition | 2 driving cycle
|
Diagnostic Circuit Diagram
Signal Waveform & Data
Monitoring CAN HIGH and LOW simultaneously is important in monitoring CAN communication waveform. When CAN HIGH signal rise to 3.5V and LOW signal drops to 1.5V - voltage difference between HIGH and LOW signal is 2V - at BUS IDLE state(DIGITAL "1") whose reference voltage is 2.5V, "0" is recognized. Besides, comparing HIGH and LOW signal if opposite waveform is detected with the reference voltage of 2.5V, Check if current CAM signal is transfers correctly. Continuous "0"signal above 6BIT means the occurence of error in CAN communication. 1BIT is easily distinguished as calculating the time when "SOF"(START OF FRAME) which notifies the start of frame occurs. Check if "0"signal above 6BIT is detected continuously when monitoring CAN communication waveform.