Mitsubishi Outlander: General Information, Service Precautions

General Information

CAN, an abbreviation for Controller Area Network, is an ISO-certified international standard for a serial multiplex communication protocol*. A communication circuit employing the CAN protocol connects each electric control module (ECU), and sensor data can be shared among, which enables more reduction in wiring.

NOTE: *: The regulations have been decided in detail, from software matters such as the necessary transmission rate for communication, the system, data format, and communication timing control method to hardware matters such as the harness type and length and the resistance values.

CAN offers the following advantages.

• Transmission rates are much faster than those in conventional communication (up to 1 Mbps), allowing much more data to be sent.
• It is exceptionally immune to noise, and the data obtained from each error detection device is more reliable.
• Each ECU connected via the CAN communicates independently, therefore if the ECU enters damaged mode, communications can be continued in some cases.

STRUCTURE

• With OUTLANDER, for the first time with MMC, a gateway function has been integrated to ETACS-ECU as the network central ECU.
• The CAN system consists of the following three networks: CAN-B (middle-speed body network), CAN-C (high-speed power train network), and the diagnosis CAN-C (diagnosis exclusive network).

  Each ECU is connected to one of the networks depending on its functions.

• The CAN bus line consists of two lines, CAN_L and CAN_H (CAN Low and CAN High, respectively), as well as two terminal resistors (A twisted-pair cable, highly resistant to noise, is used for the communications line).
• The CAN bus line connecting two dominant ECUs is the main bus line, and the CAN bus line connecting each ECU is the sub-bus line.
• With CAN-C, the terminal resistors are incorporated in ECU. Resistors with approximately 120 ohms is used for the dominant ECU, and that with 3.0 kΩ is used for the non-dominant ECU.

  NOTE:

  • Dominant ECU: ETACS-ECU and engine control module
  • Non-dominant ECU: ECU and sensor on CAN-C network, excluding ETACS-ECU and engine control module
• To the CAN bus line, ECU, sensor, and data link connector are connected as follows for each network.

  CAN-B

  • A/C-ECU
  • SRS-ECU
  • Occupant classification-ECU
  • Radio and CD player <vehicles with radio and CD player>
  • Radio and CD changer <vehicles with radio and CD changer>
  • CAN box unit <vehicles with MMCS>
  • Satellite radio tuner <vehicles with satellite radio>
  • WCM <vehicles without KOS>
  • KOS-ECU <vehicles with KOS>
  • Combination meter

  CAN-C

  • AWD-ECU <Electric controlled AWD>
  • AWC-ECU <S-AWC>
  • Steering wheel sensor <vehicles with ASC>
  • ABS-ECU <vehicles without ASC>
  • ASC-ECU <vehicles with ASC>
  • Transaxle control module (TCM) <CVT, A/T>
  • Engine control module (ECM)

  DIAGNOSIS CAN-C

  • Data link connector

Special Tools

Test Equipment

Service Precautions

Precautions On How To Repair The Can Bus Lines

PRECAUTIONS ON HOW TO REPAIR THE CAN BUS LINES

• If the CAN bus line(s) are repaired, renew all the twisted wires between the end connectors. If the wiring harness is partially repaired, or only CAN_L or CAN_H line is repaired, noise suppression is deteriorated, causing a communication error.

• If the connector or wire on the main bus line or the sub-bus wire is replaced, the frayed end of the twisted wire should be within 10 cm (4 inches) from the connector. If it exceeds 10 cm (4 inches), twist the wiring harness just like the original twisted wire. If the frayed end exceeds 10 cm (4 inches), noise suppression is deteriorated, causing a communication error.

• If a sub-bus line is repaired, splice a new wire directly into the main bus line. If a new wire is spliced into the sub-bus line, which is connected to another device, the CAN communication will be disabled.

PRECAUTIONS ON HOW TO REPAIR THE TERMINATOR RESISTOR

If one-side terminator resistor is broken, the CAN communication will continue although noise suppression is deteriorated. No diagnostic trouble code may be set even if the terminator resistor was broken. If a damage is found, replace the ECU which incorporates the defective terminator resistor.

CAN BUS LINE REPAIR HARNESS (PART NAME AND NUMBER)

EXPLANATION ABOUT THE SCAN TOOL (M.U.T.-III) CAN BUS DIAGNOSTICS

Scan tool MB991958 CAN bus diagnostics carries out the two checks below automatically, and then displays current condition of the CAN bus lines according to the check results.

CAN BUS LINE DIAGNOSTIC FLOW

1. Scan tool CAN bus diagnostics

Scan tool MB991958 diagnoses CAN bus lines in accordance with the following strategy.

NOTE: After you determine whether the CAN-C lines are in good condition, then determine whether the CAN-B lines are in good condition.

Then confirm each judgment result on the scan tool screen.

1. Check that the ETACS-ECU sets a diagnostic trouble code.

   You can narrow down the points to be diagnosed by confirming an ETACS-ECU diagnostic trouble code.

2. Checking the communication condition of ECUs.

   Scan tool MB991958 narrows down troubles in circuit by itself. Its strategies are as follows.

Reference circuit

2. Pinpoint possible trouble spot according to diagnostic trouble code.

If diagnostic trouble code related to CAN communication is set as past trouble, isolate opens as described below.

NOTE: If you pinpoint trouble spot according to diagnostic trouble code, you should use time-out diagnostic trouble code. Diagnostic trouble code related to failure information is set when the data to be set contains an error, so CAN bus line itself is probably normal.

NOTE: Time-out diagnostic trouble codes are stored in each ECU memory individually. Therefore, it is possible that these diagnostic trouble codes have not been set simultaneously. If the trouble spot cannot be found when you diagnose by judging from multiple diagnostic trouble codes, check the communication lines between each ECU.

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