DTC U0122: Lost Communication with Vehicle Dynamics Control Module; DTC U0129: Lost Communication with Brake System Control Module: Procedure

1. Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
   WARNING:

   Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to disable the SRS system.

   NOTE:

   When disconnecting the cable, some systems need to be initialized after the cable is reconnected, refer to INITIALIZATION

NEXT: Go to next step 

1. Disconnect the A24 master cylinder solenoid (skid control ECU) connector.
   Fig 1: Identifying A24 Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   A24-11 (CANH) - A24-25 (CANL)	Engine switch off	54 to 69 Ω

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Skid Control ECU)

NG → REPAIR OR REPLACE SKID CONTROL ECU BRANCH WIRE OR CONNECTOR (CANH, CANL) 

OK: Go to next step 

1. Connect the cable to the negative (-) battery terminal.
   NOTE:

   When disconnecting the cable, some systems need to be initialized after the cable is reconnected, refer to INITIALIZATION

2. Disconnect the A24 and A25 master cylinder solenoid (skid control ECU) connectors.
   Fig 2: Identifying A24 And A25 Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A24-1 (GND1) - Body ground	Always	Below 1 Ω
   A24-32 (GND2) - Body ground
   A25-4 (GND3) - Body ground

4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Switch Condition	Specified Condition
   A24-2 (+BM1) - Body ground	Always	11 to 14 V
   A24-31 (+BS) - Body ground
   A25-2 (+BM2) - Body ground
   A24-46 (IG1) - Body ground	Engine switch on (IG)	11 to 14 V
   A25-1 (IG2) - Body ground

   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Skid Control ECU)

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   4