C1616 CAN Bus Off - Automotive Diagnosis

COMPONENT LOCATION

GENERAL DESCRIPTION

EPS CM controls warning lamp by sending a signal via CAN line. After sending a message, EPS CM checks signal about whether other ECU receives a signal correctly. If EPS CM receives signal from other ECU it recognizes that a message was transmitted normally.

DTC DESCRIPTION

EPS CM sets this code If EPS doesn′t transmit or receive a message normally.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Check signal

Open or short in CAN line

Enable conditions

IG ON

Threshold value

EPS CM can’t receive signal from other ECU

Fail Safe

–

Restoration conditions

EPS CM receives signal from other ECU

DIAGNOSTIC CIRCUIT DIAGRAM

TERMINAL AND CONNECTOR INSPECTION

1.	Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage

2.	Thoroughly check all connectors (and connections) for looseness, bending, corrosion, contamination, deterioration, and/or damage.

Has a problem been found ?

	▶ Repair as necessary and then go to “Verification of Vehicle Repair” procedure.
	▶ Go to “CAN Signal Circuit Inspection” procedure.

CAN SIGNAL CIRCUIT INSPECTION

■ Short Check (to ground)

1.	Ignition “OFF” & Engine “OFF”.

2.	Disconnect the EPS CM connector.

Measure resistance between CAN LOW terminal, CAN HIGH terminal of the EPS CM harness connector and chassis ground.

∞ Ω

Is the measured resistance within specifications?

	▶ Go to next procedure.
	▶ Go to next procedure. If abnormal resistance is detected in CAN HIGH circuit, Repair short to ground in CAN HIGH circuit If abnormal resistance is detected in CAN LOW circuit, Repair short to ground in CAN LOW circuit .

■ CAN BUS Resistance Check

1.	Ignition “OFF” & Engine “OFF”.

2.	Disconnect the EPS CM and PCM connector.

Measure resistance between CAN LOW terminal and CAN HIGH terminal of the EPS CM harness connector.

Approx. 120Ω

Is the measured value within specifications?

	▶ Go to “Component Inspection” procedure.
	▶ In case of the resistance “approx. 1Ω” : Repair mutual short in CAN signal circuit of the EPS CM and then go to “Verification of vehicle Repair” procedure. In case of the resistance “∞ Ω” : Repair open in CAN signal circuit of the EPS CM In case of the resistance “approx. 120 Ω” : Check the resistances(122Ω) in I/P junction box and PCM, repair as necessary

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 steering column & EPS unit assembly check for proper operation. If problem is corrected, replace steering column & EPS unit assembly
	▶ Fault is intermittent caused by faulty EPS CM or was repaired and EPS CM memory was not cleared.

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