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Home >> Toyota >> 2021 >> Prius LE AWD-e >> Repair and Diagnosis (Single Page) >> Brakes >> Traction Control >> Electronically Controlled Brake System - Diagnostic Codes (2 Of 5) >> Electronically Controlled Brake System >> DTC C1311: Open Circuit in Main Relay 1; DTC C1312: Short Circuit in Main Relay 1 [12/2018 - ] >> Typical Enabling Conditions
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Typical Enabling Conditions

C12FA (CASE 1)

Monitor runs whenever the following DTCs are not stored None
All of the following conditions are met A, B and C
A. Skid control ECU (brake booster with master cylinder assembly) state Normal
B. Command to main relay On
C. Either of the following conditions is met a or b
a. Both of the following conditions are met -
Power switch Off
Brake system voltage 1 (VM1) Higher than 6.92 V
b. All of the following conditions are met -
Power switch On (READY)
Brake system voltage 1 (VM1) Higher than 6.92 V
IG1 voltage Higher than 9.54 V
C12FA (CASE 2)

Monitor runs whenever the following DTCs are not stored None
All of the following conditions are met -
Skid control ECU (brake booster with master cylinder assembly) state Initial check
Command to main relay On
Brake system voltage 1 (VM1) Higher than 6.92 V
C12FB (CASE 1)

Monitor runs whenever the following DTCs are not stored None
Both of the following conditions are met -
Skid control ECU (brake booster with master cylinder assembly) state Normal
Command to main relay Off
C12FB (CASE 2)

Monitor runs whenever the following DTCs are not stored None
Both of the following conditions are met -
Skid control ECU (brake booster with master cylinder assembly) state Initial check
Command to main relay Off