3.
Has a problem been found?
▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Go to "Signal Circuit Inspection" procedure.
The HECU send requirement data, such as Torque reduction, the number of fuel cut cylinders, and TCS control requests, to the PCM(ECM ＆ TCM) through CAN bus line. The 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 TCS 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 re-initialization is tried for 15 times in sequence without success.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Open or short monitoring | ● Open or short circuit in CAN line ● Inoperative HECU |
Monitoring Period | ● Continuous | |
Enable Conditions | ● A CAN BUS off fault is established if re-initialization is tried for 15 times in sequence without success. | |
Fail Safe | ● Inhibit the ESP control and ABS/EBD control is available. Meanwhile, stop checking the ESP switch failure under the ESP control. |
Many malfunctions in the electrical system are caused by poor harness(es) and terminals. 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 damageage.
Has a problem been found?
▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Go to "Signal Circuit Inspection" procedure.
Ignition "OFF".
Disconnet the HECU harness connector.
Measure resistance between terminal "14" of the HECU harness connector and terminal "35" of the HECU harness connector.
Specification : Approx. 60Ω
Is the measured resistance within specifications?
▶ Fault is intermittent caused by open or short in CAN signal harness or was repaired and HECU memory wasnot cleared. go to "CAN Bus Short (to ground) Inspection" procedure.
▶ Check for open or short in CAN signal harness between terminal "14" of the HECU harness connector and terminal "35" of the HECU harness connector. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
Ignition "OFF".
Disconnet the HECU harness connector.
Measure resistance between terminal "14, 35" of the HECU harness connector and chassis ground.
Specification : Approx. ∞ Ω
Is the measured resistance within specifications?
▶ Go to "CAN Bus Short (to battery) Inspection" procedure.
▶ Check for short to ground in CAN HIGH signal harness in case of abnormal resistance measured betweenterminal "35" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Check for short to ground in CAN LOW signal harness in case of abnormal resistance measured betweenterminal "14" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
Ignition "OFF".
Disconnet the HECU harness connector.
Measure voltage between terminal "14, 35" of the HECU harness connector and chassis ground.
Specification : Below. 0.2 V
Is the measured resistance within specifications?
▶ Go to "CAN Bus Short (between HIGH and LOW) Inspection" procedure.
▶ Check for short to battery in CAN HIGH signal harness in case of abnormal resistance measured betweenterminal "14" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ Check for short to battery in CAN LOW signal harness in case of abnormal resistance measured betweenterminal "35" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
Ignition "OFF".
Disconnet all the connetor related to CAN such as HECU, PCU, EPS, ECS harness connector.
Measure resistance between terminal "14, 35" of the HECU harness.
Specification : Approx. 120 Ω
Is the measured resistance within specifications?
▶ Go to "Component Inspection" procedure.
▶ Check for short in CAN signal harness between terminal "14" of the HECU harness connector and terminal "35" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.
Ignition "OFF".
Ignition "ON".
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 faulty HECU or was repaired and HECU memory was not cleared. 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
Are any DTCs present?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
