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U0121 Lost Communication With Anti-Lock Brake System (ABS) Control Module

AutoHex Online Help: Hyundai VERACRUZ/ix55(EN) 2011
Component Location
General Description

CAN communication is a parallel circuit to interchange information among each units. CAN communication can share much information with units more faster and more efficiently by using specified language. CAN-High line is twisted with CAN-Low line as a purpose in preventing from a noise. The operating duty of EMC is maintained at 100 : 0 (2WD) for guaranteeing stabilized driving force, accuracy of the control during inside ABS, FTCS, ESP control.



DTC Description

This code related to communication line between HECU(ABS) and "4WD-ECM" is set when CAN signal from HECU(ABS) can't received for more than 1sec or ECU internal error occur. If failure is detected "4WD-ECM" prohibits the "ITCC" control and cuts the current to control coil.

DTC Detecting Condition

Item

Detecting Condition

Possible Cause

DTC Strategy

? Wheel Speed Signal error

? Connector looseness and poor terminal to wire connection.

? CAN HIGH/LOW circuit open/short.

? Faulty CAN MODULE.(ABS)

? Faulty 4WD-ECM .

Threshold Value

? Condition1: Wheel speed signal value is invalid (over 511.875km/h), and maintained over 0.5 sec.

? Conditon2: Data can't be received in 0.5 sec.

? Condition3: No receiving of data for 0.5 sec after ignition is turned ON.

Fail Safe

? Change into 2WD mode.

Diagnostic Circuit
Signal Waveform

FIG.1) CAN Signal : high & low