DTC U0129: Lost Communication with Brake System Control Module [08/2014 - ]: Procedure

1. Reconfirm DTCs.

   HINT: 

   If DTC U1002 is output from PM2 Gateway of the power management control ECU, this indicates a power management bus malfunction. Troubleshoot for DTC U1002 and check for malfunctions in the power management bus.

   Result

   Result	Proceed to
   U1002 is not output from power management control ECU (Techstream display/PM2 Gateway)	A
   U1002 is output from power management control ECU (Techstream display/PM2 Gateway)	B

Result:  B

B 

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC 

(See article. Refer to DTC U1002: Lost Communication with Gateway Module (Power Management2) [08/2014 - ] )

Result:  A

A 

See step  2

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.

Result:  NG

NG 

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC 

(See article. Refer to DTC C1241/41: Low Battery Positive Voltage; DTC C1242/42: Open in IG1 / IG2 Power Source Circuit [08/2014 - ] )

Result:  OK

OK 

See step  3

1. Turn the power switch off.
2. Disconnect the skid control ECU connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   A61-35 (CA2H) - A61-34 (CA2L)	Power switch off	54 to 69 Ω

   TEXT IN ILLUSTRATION
   
   

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

Result:  OK

OK 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) 

(See article. Refer to REMOVAL [08/2014 - ] )

Result:  NG

NG 

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (SKID CONTROL ECU)