DTC U0129: Lost Communication with Brake System Control Module [11/2016 - ]: Procedure

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.

   Chassis > ABS/VSC/TRAC > Trouble Codes 

   Result

   Result	Proceed to
   DTC C1242 is not output	A
   DTC C1242 is output	B

Result: 

B 

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC. Refer to  DTC C1241/41: Low Battery Positive Voltage; DTC C1242/42: Open in IG1 / IG2 Power Source Circuit [11/2016 - ] 

Result: 

A 

See step  2

1. Reconfirm DTCs.

   Powertrain > Hybrid Control > Trouble Codes 

   HINT: 

   If the hybrid vehicle control ECU assembly outputs DTC U0100 and DTC U0129, check the branch circuit of local bus.

   Result

   Result	Proceed to
   The hybrid vehicle control ECU assembly outputs only DTC U0129. (Techstream display: Hybrid Control)	A
   The hybrid vehicle control ECU assembly outputs DTC U0100 and U0129. (Techstream display: Hybrid Control)	B

Result: 

B 

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC. Refer to  DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0129: Lost Communication with Brake System Control Module; DTC U0293: Lost Communication with Hybrid Vehicle Control System [11/2016 - ]  

Result: 

A 

See step  3

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the A63 skid control ECU assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A63-10 (CA2H) - A63-11 (CA2L)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Result: 

NG 

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

Result: 

OK 

See step  4

1. Disconnect the A62, A64 and A65 skid control ECU assembly connectors.
2. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

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

   -

   -

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A62-1 (GND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
   A63-3 (GND2) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
   A63-1 (GND3) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
   A64-3 (GND4) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
   A64-1 (GND5) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω
   A65-3 (GND6) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

3. Reconnect the cable to the negative (-) auxiliary battery terminal.
4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A63-5 (+BI3) - Body ground	Power switch off	11 to 14 V
   A63-4 (+BI1) - Body ground	Power switch off	11 to 14 V
   A63-2 (IG1) - Body ground	Power switch on (IG)	11 to 14 V
   A65-6 (+BI4) - Body ground	Power switch off	11 to 14 V
   A65-5 (+BI2) - Body ground	Power switch off	11 to 14 V
   A64-5 (IG2) - Body ground	Power switch on (IG)	11 to 14 V

Result: 

OK 

REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [02/2014 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)