DTC C137B-A3: Brake System Control Module "A" System Voltage System Voltage High [12/2019 - ]: Procedure

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to No. 2 Skid Control ECU (Brake Actuator Assembly))

   OK

   The connector is securely connected.

2. Disconnect the A57 No. 2 skid control ECU (brake actuator assembly) connector.
3. Check both the connector case and the terminals for deformation and corrosion.

   OK

   No deformation or corrosion.

4. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A57-14 (+BS) - Body ground	Always	11 to 14 V
   A57-14 (+BS) - A57-1 (GND1)	Always	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  2

1. Reconnect the A57 No. 2 skid control ECU (brake actuator assembly) connector.
2. Clear the DTCs.

   Chassis > Brake/EPB > Clear DTCs 

3. Turn the ignition switch off.

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  3

1. Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.
2. Check if the same DTC is output.

   Chassis > Brake/EPB > Trouble Codes 

   Result

   Result	Proceed to
   DTC C137B-A3 is not output.	A
   DTC C137B-A3 is output.	B

Result: 

A 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2019 - ] 

Result: 

B 

REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2019 - 10/2022]  , or refer to  REMOVAL [10/2022 - 11/2023]  , or refer to  REMOVAL [11/2023 - ]