DTC U0129: Lost Communication with Brake System Control Module (2016 - 2017): 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.

   OK

   DTC C1241 is not output.

Result:  NG

NG 

Go To Diagnosis Procedure Indicated By Output DTC 

(efer to DIAGNOSTIC TROUBLE CODE CHART (2016 - 2017) )

Result:  OK

See step  Reconfirm DTC Output

1. Reconfirm DTCs.

   HINT: 

   If the hybrid vehicle control ECU assembly outputs DTC U0100 and DTC U0129, check the main circuit of sub bus 15.

   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

B 

Go To Diagnosis Procedure Indicated By Output DTC 

(efer to DTC U0100: Lost Communication with ECM / PCM "A"; DTC U0129: Lost Communication with Brake System Control Module; DTC U0293: Lost Communication with HV ECU (2016 - 2017) )

Result:  A

A 

See step  3

1. Disconnect the cable from the negative (-) auxiliary battery terminal.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

2. Disconnect the A24 brake booster with master cylinder assembly (skid control ECU) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A24-35 (CA2H) - A24-34 (CA2L)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   TEXT IN ILLUSTRATION
   
   

   *a	Front view of wire harness connector (to Brake Booster with Master Cylinder Assembly (Skid Control ECU)

Result:  OK

OK 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY 

(efer to REMOVAL (2016 - 2017) )

Result:  NG

NG 

REPAIR OR REPLACE CAN BRANCH LINE OR CONNECTOR (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY)