DTC U0129: Lost Communication with Brake System Control Module: Procedure

1. Reconfirm DTCs.

   HINT: 

   If power management bus DTC U1002 is output from the power management control ECU (Techstream display/Power Management1), troubleshoot for U1002 and check for malfunctions in the CAN No. 2 main bus circuit.

   Result

   Result	Proceed to
   U1002 is not output from power management control ECU (Techstream display/Power Management1)	A
   U1002 is output from power management control ECU (Techstream display/Power Management1)	B

B → See step   5 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Chassis/ABS/VSC/TRAC/Trouble Codes.

   OK

   DTC C1241 is not output.

NG → See step   6 

OK: Go to next step 

1. Turn the power switch off.
2. Disconnect the brake booster with master cylinder (skid control ECU) connector.
   Fig 1: Identifying A60 Brake Booster With Master Cylinder (Skid Control ECU) Connector CAN Bus Wire For Disconnection

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *1	Front view of wire harness connector (to Brake Booster with Master Cylinder)

3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A60-35 (CA2H) - A60-34 (CA2L)	Power switch off	54 to 69 Ω

NG → REPAIR OR REPLACE CAN BUS BRANCH WIRE OR CONNECTOR (SKID CONTROL ECU) 

OK → See step   4