Component Location
General Description
This vehicle has a Control Area Network CAN bus sytem. CAN is a methed of comunication between the ECM and other control units. Some of the other control units that could be on the CAN lines are ECM, TCM, ESP ECM, ABS and BCM. The CAN consist of a 2 wire network, a high and a low wire. A vehicle can have two CAN sytems. A High Speed CAN for engine, trans and ABS and a Low Speed CAN for BCM and windows.
DTC Description
Checking CAN communication, under detecting condition, if an CAN communication error between ECM and IDB is detected. ECM sets U0105.
DTC Detecting Condition
Item | Detecting Condition | Possible cause |
DTC Strategy | Check CAN message from IDB
| Faulty IDB CAN communication line between ECM and IDB |
EnableConditions | Engine Run Time = 2sec.
Ignition Voltage = 11V
|
Threshold value | CAN communicatin error with IDB
|
Diagnosis Time | Continuous
|
MIL On Condition | 3 driving cycle
|
Diagnostic Circuit Diagram
Signal Waveform & Data
Fig.1) Can communication waveform at idle
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 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.