Dtc U0129 Lost Communication With Brake System Control Module

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

PRECAUTION

DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL

CHECK FOR OPEN IN CAN BUS WIRE (SKID CONTROL ECU CAN BRANCH WIRE)

CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - BATTERY AND BODY GROUND)

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

HINT:

Operating the ignition switch, any switches or any doors triggers related ECU and sensor communication with the CAN, which causes resistance variation.

NOTICE:

After turning the ignition switch off, waiting time may be required before disconnecting the cable from the battery terminal. Therefore, make sure to read the disconnecting the cable from the battery terminal notice before proceeding with work (Click here).

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

   CAUTION:

   For vehicles with an SRS system:

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

   NOTICE:

   When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Click here).

1. Disconnect the A24 master cylinder solenoid (skid control ECU) connector.
   

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)	Ignition switch off	54 to 69 Ω

   Text in Illustration

   *a	Front view of wire harness connector (to Master Cylinder Solenoid [Skid Control ECU])

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

   NOTICE:

   When disconnecting the cable, some systems need to be initialized after the cable is reconnected (Click here).

2. Disconnect the A25 master cylinder solenoid (skid control ECU) connector.
   

3. 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	Always	11 to 14 V
   A25-2 (+BM2) - Body ground	Always	11 to 14 V
   A24-46 (IG1) - Body ground	Ignition switch ON	11 to 14 V
   A25-1 (IG2) - Body ground	Ignition switch ON	11 to 14 V

4. 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	Always	Below 1 Ω
   A25-4 (GND3) - Body ground	Always	Below 1 Ω