Brake Booster (Skid Control ECU) Communication Stop Mode [11/2021 - 12/2022]: Procedure

1. Disconnect the cable from the negative (-) auxiliary battery terminal.
2. Disconnect the A5 brake booster with master cylinder assembly (No. 1 skid control ECU) connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A5-38 (CA1H) - A5-39 (CA1L)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR 

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
   A5-28 (GND1) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

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	Switch Condition	Specified Condition
   A5-14 (+BI1) - Body ground	Ignition switch off	11 to 14 V
   A5-15 (BS) - Body ground	Ignition switch off	11 to 14 V
   A5-31 (IG1) - Body ground	Ignition switch ON	11 to 14 V
   A5-42 (IG2) - Body ground	Ignition switch ON	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (NO. 1 SKID CONTROL ECU). Refer to  REMOVAL [11/2021 - 12/2022] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)