DTC Logic

CAN (Controller Area Network) is a serial communication line for real time applications. It is an on-vehicle multiplex communication line with high data communication speed and excellent error detection ability. Modern vehicle is equipped with many electronic control unit, and each control unit shares information and links with other control units during operation (not independent). In CAN communication, control units are connected with 2 communication lines (CAN H-line, CAN L-line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

CAN Communication Signal Chart. Refer to CAN Communication Signal Chart

DTC DETECTION LOGIC

DTC No.	M.U.T.-III SE screen items (Trouble diagnosis content)	DTC Detection Condition
U2143-87	CAN comm err (VCM/HCM) [Controller area network communication error (VCM/HCM)]	Diagnosis condition	When electric motor switch is ON.
		Signal (terminal)	CAN communication signal
		Threshold	Air bag diagnosis sensor unit cannot communicate CAN communication signal.
		Diagnosis delay time	2 seconds or more.

POSSIBLE CAUSE

CAN communication system

FAIL-SAFE

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DTC CONFIRMATION PROCEDURE

1.CHECK DIAGNOSTIC TROUBLE CODE RESULT

With M.U.T.-III SE

Electric motor switch ON and wait for 2 seconds or more.
Perform "Diagnostic Trouble Code" mode of "AIR BAG" using M.U.T.-III SE.

Is malfunctioning part detected?

Refer to Diagnosis Procedure

-1To check malfunction symptom before repair: Refer to Intermittent IncidentIntermittent Incident

-2Confirmation after repair: INSPECTION END