CAN Communication System: System Description
- CAN communication is a multiplex communication system. This enables the system to transmit and receive large quantities of data at high speed by connecting control units with two communication lines (CAN-H and CAN-L).
- Control units on the CAN network transmit signals using the CAN communication control circuit. They receive only necessary signals from other control units to operate various functions.
- CAN communication lines adopt twisted-pair line style (two lines twisted) for noise immunity.
DIAG On CAN: Description
"Diag on CAN" is a diagnosis using CAN communication instead of previous DDL1 and DDL2 communication lines, between control units and diagnosis unit.
Abbreviation List
Abbreviation in CAN communication signal chart, and the diagnosis sheet are as per the following list.
| Abbreviation | Unit name | Select system (SDT) | Bus check (SDT) |
|---|---|---|---|
| 4WD | Transfer control unit | 4WD | AWD/4WD |
| A-BAG | Air bag diagnosis sensor unit | Airbag | |
| ABS | ABS actuator and electric unit (control unit) | ABS / ESP® | VDC/TCS/ABS |
| BCM | BCM | BCM | BCM/SEC |
| DIFF | Differential lock control unit | Diff Lock | DIFF LOCK |
| DLC | Data link connector | ||
| ECM | ECM | Engine / Powertrain | ECM |
| IPDM-E | IPDM E/R | IPDM E/R | IPDM E/R |
| M&A | Combination meter | Meter / M&A | METER/M&A |
| STRG | Steering angle sensor | STRG | |
| TCM | TCM | AT | TCM |
ABBREVIATION CHART
Scheme 3
Each control unit passes an electric current to the termination circuits when transmitting CAN communication signal. The termination circuits produce an electrical potential difference between CAN-H and CAN-L. CAN communication system transmits and receives CAN communication signals by the potential difference.
| Component | Description |
|---|---|
| Main line | CAN communication line between splices |
| Branch line | CAN communication line between splice and a control unit |
| Splice | A point connecting a branch line with a main line |
| Termination circuit | Refer to [ CAN COMMUNICATION CONTROL CIRCUIT ]. |
COMPONENT DESCRIPTION
Scheme 4
| Component | System description |
|---|---|
| CAN controller | It controls CAN communication signal transmission and reception, error detection, etc. |
| Transceiver IC | It converts digital signal into CAN communication signal, and CAN communication signal into digital signal. |
| Noise filter | It eliminates noise of CAN communication signal. |
| Termination circuit (1) (Resistance of approx. 120 ohms) | It produces potential difference. |
| (1) These are the only control units wired with both ends of CAN communication system. | |
| (1) | These are the only control units wired with both ends of CAN communication system. |
COMPONENT DESCRIPTION
Scheme 5
| Name | Harness | Description |
|---|---|---|
| DDL1 | Tx Rx | It is used for trouble diagnosis. (CAN-H and CAN-L are used for controlling) |
| DDL2 | K-LINE | It is used for trouble diagnosis. (CAN-H and CAN-L are used for controlling) |
| Diag on CAN | CAN-H CAN-L | It is used for trouble diagnosis and control. |
HARNESS DESCRIPTION
Scheme 6
VEHICLE EQUIPMENT IDENTIFICATION INFORMATION
Note. Check CAN system type from the vehicle shape and equipment.
