DTC C123A-00: IG1 Malfunction [11/2021 - 10/2023]: Procedure

1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

   OK

   The connector is securely connected.

2. Disconnect the A101 No. 1 skid control ECU (brake booster with master cylinder assembly) connector.
3. Check both the connector case and the terminals for deformation and corrosion.

   OK

   No deformation or corrosion.

4. Turn the ignition switch to ON.
5. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A101-31 (IG1) - Body ground	Ignition switch ON	11 to 14 V

   Result

   Result	Proceed to
   11 to 14 V.	A
   Below 11 V.	B

Result: 

A 

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

Result: 

B 

REPAIR OR REPLACE HARNESS OR CONNECTOR