Brake Booster (Skid Control ECU) Communication Stop Mode [11/2023 - ]: Procedure

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the A44 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A44-38 (CA1H) - A44-39 (CA1L)	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 No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (NO. 1 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY)) 

Result: 

OK 

See step  2

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A44-28 (GND1) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to No. 1 Skid Control ECU (Brake Booster with Master Cylinder Assembly))

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A44-14 (+BI1) - Body ground	Ignition switch off	11 to 14 V
   A44-31 (IG1) - Body ground	Ignition switch ON	11 to 14 V
   A44-42 (IG2) - Body ground	Ignition switch ON	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE NO. 1 SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) 

Refer to REMOVAL [11/2023 - ]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)