3.
Has a problem been found?
 | ▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure. |
 | ▶ Go to "CAN Signal Circuit Inspection" procedure. |
The HECU send requirement data, such as Torque reduction, the number of fuel cut cylinders, and ESP 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 ESP control time, in order not to increase power which causes a Kickdown shift.
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.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Open or short circuit monitoring | ● Open or short circuit in CAN line ● Faulty HECU |
Enable Conditions | ● In case CAN BUS off state continued for more than 100ms. | |
Fail Safe | ● Inhibit the ESP control and allow the ABS/EBD control. ● The ESP warning lamp is activated. |
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.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
| ▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure. |
| ▶ Go to "CAN Signal Circuit Inspection" procedure. |
Ignition "OFF" & Engine "OFF".
Disconnect the HECU connector.
Measure resistance between CAN LOW terminal, CAN HIGH terminal of the HECU harness connector and chassis ground.
Specification : Approx. 0Ω
Is the measured resistance within specifications?
| ▶ Go to next procedure. |
| ▶ If abnormal resistance is detected in CAN HIGH circuit, Repair short to ground in CAN HIGH circuit and then go to "Verification of vehicle Repair" procedure. If abnormal resistance is detected in CAN LOW circuit, Repair short to ground in CAN LOW circuit and then go to "Verification of vehicle Repair" procedure. |
Ignition "OFF" & Engine "OFF".
Disconnect the HECU connector.
Measure resistance between CAN LOW terminal and CAN HIGH terminal of the HECU harness connector.
Specification : Approx. 60Ω
Is the measured value within specifications?
| ▶ Go to "Component Inspection" procedure. |
| ▶ In case of the resistance "approx. 1Ω" : Repair mutual short in CAN signal circuit of the HECU and then go to "Verification of vehicle Repair" procedure. In case of the resistance "∞ Ω" : Repair open in CAN signal circuit of the HECU and then go to "Verification of vehicle Repair" procedure. In case of the resistance "approx. 120 Ω" : Check the resistances(122Ω) in I/P junction box and ECM, repair as necessary and then go to "Verification of vehicle Repair" procedure. |
Ignition "OFF"
Ignition "ON" & Engine "OFF".
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode.
Using a scantool, Clear DTC.
Select "Diagnostic Trouble Codes(DTCs)" mode again.
Are any DTCs present ?
| ▶ Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure. |
| ▶ Fault is intermittent caused by poor connection in CAN signal harness and/or HECU's connector. Go to "Verification of Vehicle Repair" procedure. |
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information.
Using a scantool, Check DTC present.
Are any DTCs present ?
| ▶ Go to the applicable troubleshooting procedure. |
| ▶ System performing to specification at this time. |
