DTC Description
CAN (Controller Area Network) is a serial communication line for real time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H line, CAN L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.
DTC DETECTION LOGIC
| DTC | CONSULT screen terms (Trouble diagnosis content) | DTC detecting condition | ||
|---|---|---|---|---|
| U0122 | 00 | VDC MDL (Lost communication with vehicle dynamics control module) | Diagnosis condition | Ignition switch ON |
| Signal (terminal) | CAN communication | |||
| Threshold | When ECM is not transmitting or receiving CAN communication signal of OBD (emission related diagnosis) with ABS actuator and electric unit (control unit) | |||
| Diagnosis delay time | 2 seconds or more | |||
POSSIBLE CAUSE
Harness or connectors (CAN communication line is open or shorted)
FAIL-SAFE
When a DTC is detected, ECM executes a mode (in the Fail-safe mode) applicable to the DTC. The fail-safe mode has the preset traveling control mode (accelerator angle variation and engine output limit) and device fix mode.
| Fail safe mode | Vehicle behavior | |
|---|---|---|
| Traveling control mode | Accelerator angle variation control | ECM controls the accelerator pedal depression speed to make it slower than actual speed. This causes a drop in accelerating performance and encourages the driver to repair malfunction.
NOTE:
|
| Combustion control mode | Stratified charge combustion control at starting | No stratified charge combustion at starting (cold start). |