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:

   • w/ Navigation System:

     After the engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.

   • 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 Skid Control ECU connector Terminal

   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

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: Checking Harness And Connector (Skid Control ECU - Battery And Body Ground)

   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

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   4