C1612 ABS CAN Time-out TCM - Automotive Repair Guides & Equipment

COMPONENT LOCATION

GENERAL DESCRIPTION

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.

DTC DESCRIPTION

The HECU checks the CAN communcation lines for normal ESP 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 TCM

Open or short in CAN communication line

Poor connection

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 ESP control and allow the ABS/EBD control.

The ESP warning lamp is activated.

DIAGNOSTIC CIRCUIT 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
	▶ 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 terminal(LOW terminal) of the HECU harness connector and CAN HIGH terminal(LOW terminal) terminal of the TCM harness connector.

Approx. below 1Ω

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

COMPONENT 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) . If NG, replace HECU .
	▶ Fault is intermittent caused by faulty HECU, faulty PCM(TCM) or was repaired and HECU memory was not cleared.

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