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Home >> Lexus >> 2021 >> LS 500h RWD >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System (W/O Advanced Park) - Diagnostic Codes (2 Of 3) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/o Advanced Park) >> DTC C1311: Open Circuit in Main Relay 1; DTC C1312: Short Circuit in Main Relay 1; DTC C1313: Open Circuit in Main Relay 2; DTC C1314: Short Circuit in Main Relay 2 [10/2020 - 10/2023] >> Description

DTC C1311: Open Circuit in Main Relay 1; DTC C1312: Short Circuit in Main Relay 1; DTC C1313: Open Circuit in Main Relay 2; DTC C1314: Short Circuit in Main Relay 2 [10/2020 - 10/2023]: Description

The ABS main relay supplies power to the changeover solenoid and the linear solenoid.

The ABS main relay remains on for approximately 2 minutes after the power switch is turned off and the input of brake pedal operation signals stops, and supplies power to the system to keep it ready to operate.

DTC No. Detection Item INF Code DTC Detection Condition Trouble Area MIL Note
C1311 Open Circuit in Main Relay 1 1 Either of the following is detected:
  1. The ABS main relay 1 contact is not turned ON (BS01 terminal voltage less than 3.5 V) for 0.2 seconds or more when the ABS main relay 1 ON is requested while +BI1 terminal voltage is 7.5 V or more.
  2. When terminal +BI1 voltage is less than 7.5 V and the ABS main relay 1 contact is not turned ON (BS01 terminal voltage 3.5 V or more) for 0.2 seconds or more when the ABS main relay 1 ON is requested.
  • Open or short in ABS main relay 1 circuit
  • Skid control ECU assembly
 Come on INF Code 1: SAE Code C12FA
C1312 Short Circuit in Main Relay 1 3 The ABS main relay 1 contact is turned ON (BS01 terminal voltage 6.5 V or more) for 1 second or more when the ABS main relay 1 OFF is requested.
  • Short in ABS main relay 1 circuit
  • ABS main relay 1 internal stuck
  • Skid control ECU assembly
 Come on INF Code 3: SAE Code C12FB
C1313 Open Circuit in Main Relay 2 4 Either of the following is detected:
  1. The ABS main relay 2 contact is not turned ON (BS02 terminal voltage less than 3.5 V) for 0.2 seconds or more when the ABS main relay 2 ON is requested while +BI2 terminal voltage is 7.5 V or more.
  2. When terminal +BI2 voltage is less than 7.5 V and the ABS main relay 2 contact is not turned ON (BS02 terminal voltage 3.5 V or more) for 0.2 seconds or more when the ABS main relay 2 ON is requested.
  • Open or short in ABS main relay 2 circuit
  • Skid control ECU assembly
 Come on INF Code 4: SAE Code C130C
C1314 Short Circuit in Main Relay 2 6 The ABS main relay 2 contact is turned ON (BS02 terminal voltage 6.5 V or more) for 1 second or more when the ABS main relay 2 OFF is requested.
  • Short in ABS main relay 2 circuit
  • ABS main relay 2 internal stuck
  • Skid control ECU assembly
 Come on INF Code 6: SAE Code C130D
DTC DETECTION CONDITIONS: C1311 INF CODE: 1

  Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition +BI1 terminal voltage is 7.5 V or more ◦ -
ABS main relay 1 on - ◦
Malfunction Status With the ABS main relay 1 on, the relay contact is off (BS01 terminal voltage is less than 3.5 V) ◦ -
The relay contact does not turn on (BS01 terminal voltage 3.5 V or more) while +BI1 terminal voltage is less than 7.5 V - ◦
Detection Time 0.2 seconds or more 0.2 seconds or more
Number of Trips 1 trip 1 trip
DTC DETECTION CONDITIONS: C1313 INF CODE: 4

  Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition +BI2 terminal voltage is 7.5 V or more ◦ -
ABS main relay 2 on - ◦
Malfunction Status With the ABS main relay 2 on, the relay contact is off (BS02 terminal voltage is less than 3.5 V) ◦ -
The relay contact does not turn on (BS02 terminal voltage 3.5 V or more) while +BI2 terminal voltage is less than 7.5 V - ◦
Detection Time 0.2 seconds or more 0.2 seconds or more
Number of Trips 1 trip 1 trip
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