Brake System > ESC(Electronic Stability Control) System

Component Location

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 communcation lines for normal ESC control, and sets this code if an TCM message is not received within 500ms.

The HECU does not detect this code until 2 seconds after the IG KEY is turned to ON.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC
Strategy

•	CAN message monitoring

•	Faulty PCM(TCM)

•	Faulty HECU

Enable
Conditions

•	In case that TCM message was not received for more than 500ms within normal voltage condition. - The Monitoring starts 2000 ms after Power Up.

Fail Safe

•	Inhibit the ESC control and allow the ABS/EBD control.

•	The ESC warning lamp is activated.

Schematic 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.

Has a problem been found?

	▶ Repair as necessary and then go to "Verification Of Vehicle Repair" procedure.
	▶ Go to "Signal circuit inspection" procedure.

Signal circuit inspection

Open Check

1.	Ignition "OFF" & Engine "OFF".

2.	Disconnect HECU and ECM connector.

Measure resistance between CAN HIGH, LOW terminal of the HECU harness connector and CAN HIGH, LOW terminal of the TCM harness connector.

Specification : Approx. 0Ω

Is the measured resistance within specifications?

	▶ Go to "Component inspection" procedure.
	▶ Repair open in CAN BUS line between HECU harness connector and TCM harness connector and then go to "Verification Of Vehicle Repair" procedure.

Component Circuit 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.

Are any DTCs present ?

	▶ Substitute with a known-good PCM (TCM) and check for proper operation. If problem is corrected, replace PCM(TCM) and then go to "Verification Of Vehicle Repair" procedure. If NG, replace HECU and then go to "Verification Of Vehicle Repair" procedure.
	▶ Fault is intermittent caused by faulty HECU, faulty PCM(TCM) or was repaired and HECU memory was ot cleared. Go to "Verification Of Vehicle Repair" procedure.

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.

Are any DTCs present ?

	▶ Go to the applicable troubleshooting procedure.
	▶ System performing to specification at this time.