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 variant 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 variant value in the memory to use for the ESP control.
The HECU checks the variant code after ignition. If a inappropriate variant code is detected or there is no variant code, a fault is detected.
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Internal monitoring | ● Inoperative HECU ● Replacement of PCM(ECM & TCM) |
Monitoring Period | ● Once during startup. | |
Enable Conditions | ● During intialization, there is no inputed valid varient code. ● No variant code stored in EEPROM. ● Receieved variant code is invalid. ● There is a difference between preset variant code and detected 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/PCM(ECM & TCM)/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".
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.