C1616 ABS CAN Bus off error - 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 communication lines for normal TCS control, and sets this code if CAN BUS OFF status is detected for more than 100ms.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Open or short circuit monitoring

Open or short circuit in CAN line

Faulty HECU

Enable Conditions

In case CAN BUS off state continued for more than 100ms.

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 “CAN Signal Circuit Inspection” procedure.

CAN SIGNAL CIRCUIT INSPECTION

■ Short Check (to ground)

1.	Ignition “OFF” & Engine “OFF”.

2.	Disconnect PCM connector and the HECU connector.

3.	Measure resistance between CAN-High terminal of PCM harness connector and CAN-High terminal of the HECU harness connector.

Measure resistance between CAN-Low terminal of PCM harness connector and CAN-Low terminal of the HECU harness connector.

Approx. below 1Ω

Is the measured value within specifications?

	▶ Go to “Check CAN communication line for short” procedure.
	▶ Repair open in the CAN communication line between PCM ECU and HECU,

■ Check CAN communication line for short

1.	Ignition “OFF” & Engine “OFF”.

2.	Disconnect PCM connector and HECU connector.

3.	Measure resistance between CAN-High terminal of PCM harness connector and chassis ground.

4.	Measure resistance between CAN-Low terminal of PCM harness connector and chassis ground.

Measure resistance between CAN-High terminal and CAN-Low of ECM/TCM harness connector.

Infinite (∞ Ω)

Is the measured value within specifications?

	▶ Go to “Component Inspection” procedure.
	▶ Repair short in the CAN communication line between PCM and HECU

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 HECU and check for proper operation. If problem is corrected, replace HECU
	▶ Fault is intermittent caused by poor connection in CAN signal harness and/or HECU’s connector.

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