DTC Troubleshooting: U0122-00
DTC U0122-00: Lost Communication With the VSA Modulator-Control Unit (wheel speed sensor signal error)
NOTE:
Before doing this troubleshooting procedure, find out if the vehicle was in a collision. If so, verify that all the required components were replaced with new components of the correct part number and were properly installed.
Before doing this troubleshooting procedure, review SRS Precautions and Procedures, General Troubleshooting Information, and 12 Volt Battery Terminal Disconnection and Reconnection.
According to the detected DTC(s), check for the power circuit and the ground circuit of the control unit which cannot communicate with the SRS unit.
Refer to the DTC shown on the display, then inspect the connectors and terminals based on the instructions.

DTC Description
DTC
U0122-00 Lost communication with the VSA modulator-control unit (wheel speed sensor signal error)
  

1.
Problem verification:

Problem verification
?1.
Clear the DTCs with the HDS.


?2.
Turn the vehicle to the ON mode, then wait for 10 seconds.

?3.
Check for DTCs with the HDS.
DTC Description
DTC
U0122-00 Lost communication with the VSA modulator-control unit (wheel speed sensor signal error)
  

Is DTC U0122-00 indicated?

     
YES
     
     
     
The failure is duplicated. Go to step 2.
     
NO
     
     
     
Intermittent failure, the system is OK at this time. Go to Troubleshooting Intermittent Failures. If another DTC is indicated, troubleshoot the DTC.?
2.
Open wire check (F-CAN_H, F-CAN_L lines):

Open wire check (F-CAN_H, F-CAN_L lines)
?1.
Turn the vehicle to the OFF (LOCK) mode.

?2.
Disconnect the negative cable from the 12 volt battery, then wait at least 3 minutes.

?3.
Disconnect the receiving control unit connector(s).
SRS unit connector A (39P)

?4.
Disconnect the transmitting control unit connector(s).
Refer to the DTC shown on the display, then disconnect the connector(s) based on the instructions (see table).

DTC
Connector
U0122-00
VSA modulator-control unit 46P connector

?5.
Check for continuity between the receiving control unit and the transmitting control unit on the F-CAN_H circuit and the F-CAN_L circuit.
Test condition
Vehicle OFF (LOCK) mode
 
Receiving control unit connector(s): disconnected
 
Transmitting control unit connector(s) for indicated DTCs: disconnected

DTC
Circuit name
Receiving control unit
Transmitting control unit
Connector
Terminal
Connector
Terminal
U0122-00
F-CAN_H
SRS unit connector A (39P)
No. 34
VSA modulator-control unit 46P connector
No. 40
F-CAN_L
No. 35
No. 28

Is there continuity?

     
YES
     
     
     
The F-CAN_H and the F-CAN_L wires are OK. Check for poor connections or loose terminals at the SRS unit and the VSA modulator-control unit. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting. If they are OK, replace the VSA modulator-control unit.
     
NO
     
     
     
Replace an open in the wire between the transmitting control unit and the SRS unit.?