There is no hardware difference of the HECU according to the vehicle's specification, just software is changed by the vehicle parameter used for ESP control. The HECU stores a classified varient code value according to the received data(a kind of engine, engine displacement, a kind of T/M). After then the HECU read a various parameter according to the stored varient value in the memory to use for the ESP control.
The HECU checks the varient code after ignition. If a inappropriate varient code is detected or there is no varient code, a fault is detected.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Internal monitoring | ● Faulty HECU ● Replacement of EMS, T/M ECU |
Monitoring Period | ● Once during startup. | |
Enable Conditions | ● During intialization, there is no inputed valid varient code. ● The EEPROM didn’t have variant coed. ● Receieved variant code is invalid. ● There is a difference between pre-inputted variant code and re-inputted variant code. | |
Fail Safe | ● The ABS/EBD/ESP functions are inhibited. ● The ABS/EBD/ESP warning lamps are activated. |
Check for improper installation of EMS/TCU/ESP.
Connect scantool to Data Link Connector(DLC).
Ignition "ON".
Go in Anti-Lock brake system (figure 1).
Perform variant code.
Disconnect scantool.
Ignition "OFF" and then ignition "ON". Go to "Component Inspection"Procedure.
Ignition "OFF".
Engine "ON".
Does warning lamp remain On?
▶ 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 the applicable troubleshooting 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.