Several control units are applied to electronically controlled vehicles. These units perform each control with informations from various sensors. Thus, sharing signal information from sensors is needed, so CAN communication type whose communication speed is high and insensitive to electrical noise by spark generation is adopted to controlling power-train(PCM(TCM/ECM), CLUSTER,ESP,4WD, EPS). CAN communication consists of CAN BUS HIGH, CAN BUS LOW and two 120? resistances in circuit.
If the 4WD ECU doesn't get some ABS/ESP signals from ABS/ESP moduel, it sets U0121.
Item
Detecting Condition
Possible cause
DTC Strategy
CAN Signal Check
Poor connection
Open or short in CAN communication line
Error in ABS/ESP unit
Error in Wheel speed sensor
Enable conditions
IG " ON" or Engine " ON "
Threshold value
It can't get some CAN signals from ABS/ESP module.
Detecting time
2 seconds