Brake System

General Description

The HECU send requirement data, such as Torque reduction, the number of fuel cut cylinders, and ESC control requests, to the Engine PCM(ECM & TCM) through CAN bus line.
The Engine PCM(ECM) performs fuel cut functions according to requests from the HECU and retards ignition timing by torque reduction requests.
The PCM(TCM) maintains current gear positions during ESC control time, in order not to increase power which causes a Kickdown shift.

DTC Description

The HECU checks the CAN communication lines for normal TCS control, and sets this code if CAN BUS OFF status is detected for more than 100ms.

DTC Detecting Condition






Diagnostic Circuit Diagram






Terminal and Connector Inspection

1. Many malfunctions in the electrical system are caused by poor harness(es) and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?






CAN Signal Circuit Inspection

Short Check (to ground)
1. Ignition "OFF" & Engine "OFF".
2. Disconnect ECM/ TCM connector and the HECU connector.
3. Measure resistance between CAN-High terminal of ECM/TCM harness connector and CAN-High terminal of the HECU harness connector.
4. Measure resistance between CAN-Low terminal of ECM/TCM harness connector and CAN-Low terminal of the HECU harness connector.

Specification :Approx. below 1Ohms

5. Is the measured value within specifications?






Check CAN communication line for short
1. Ignition "OFF" & Engine "OFF".
2. Disconnect ECM/TCM connector and HECU connector.
3. Measure resistance between CAN-High terminal of ECM/TCM harness connector and chassis ground.
4. Measure resistance between CAN-Low terminal of ECM/TCM harness connector and chassis ground.
5. Measure resistance between CAN-High terminal and CAN-Low of ECM/TCM harness connector.

Specification :Infinite (Infinity Ohms)

6. Is the measured value within specifications?






Component Inspection

1. Ignition "OFF"
2. Ignition "ON" & Engine "OFF".
3. Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode.
4. Using a scantool, Clear DTC.
5. Select "Diagnostic Trouble Codes(DTCs)" mode again.
6. Are any DTCs present ?






Verification of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode.
2. Using a scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Using a scantool, Check DTC present.
5. Are any DTCs present ?