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Home >> Lexus >> 2022 >> LS 500h AWD >> Repair and Diagnosis >> Brakes >> Parking Brake System >> Electric Parking Brake System (W/O Advanced Park) - Diagnostic Codes & Symptom Tests >> ELECTRIC PARKING BRAKE SYSTEM (w/o Advanced Park) >> DTC C13A4: Open or Short Circuit in Release Switch Circuit; DTC C13AC: Release Switch Circuit Comparison [10/2020 - 10/2023] >> Description

DTC C13A4: Open or Short Circuit in Release Switch Circuit; DTC C13AC: Release Switch Circuit Comparison [10/2020 - 10/2023]: Description

When the electric parking brake switch assembly is pulled to the release side, a release request signal is output to the parking brake ECU assembly.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory Note
C13A4 Open or Short Circuit in Release Switch Circuit
  • Diagnosis Condition:

    Electric parking brake switch assembly is operated to release side with power switch off or power switch is turned on (IG)

  • Malfunction Status:

    REL1 or REL2 terminal voltage is below 1.4 V (*) or above 9 V (*)

  • Malfunction Duration:

    Approximately 1 second

HINT: *: This value is based on the assumption that the BECU terminal voltage is 11 V.The threshold changes according to the BECU terminal voltage.For details, refer to "Threshold Changes According to BECU Terminal Voltage".
  • Electric parking brake switch assembly
  • Wire harness or connector
  • Parking brake ECU assembly
Yes An electric parking brake system malfunction is displayed on the multi-information display.
C13AC Release Switch Circuit Comparison
  • Diagnosis Condition:

    Electric parking brake switch assembly is operated to release side with power switch off or power switch is turned on (IG)

  • Malfunction Status:

    Release 1 switch and release 2 switch ON/OFF evaluations do not match

  • Malfunction Duration:

    The malfunction status repeats 5 times

  • Electric parking brake switch assembly
  • Wire harness or connector
  • Parking brake ECU assembly
Yes An electric parking brake system malfunction is displayed on the multi-information display.
DTC DETECTION CONDITION COMBINATION TABLE:C13A4 (PATTERN1, PATTERN2, PATTERN3, PATTERN4)

  Vehicle Condition
Pattern 1 Pattern 2 Pattern 3 Pattern 4
Diagnosis Condition Electric parking brake switch assembly is operated to lock side with power switch off - -
Power switch on (IG) - -
Malfunction Status REL1 terminal voltage is below 1.4 V (*) - -
REL1 terminal voltage is above 9 V (*) - -
Detection Time Approximately 1 second Approximately 1 second Approximately 1 second Approximately 1 second
Trip Count 1 trip 1 trip 1 trip 1 trip
DTC DETECTION CONDITION COMBINATION TABLE: C13A4 (PATTERN 5, PATTERN 6, PATTERN 7, PATTERN 8)

  Vehicle Condition
Pattern 5 Pattern 6 Pattern 7 Pattern 8
Diagnosis Condition Electric parking brake switch assembly is operated to lock side with power switch off - -
Power switch on (IG) - -
Malfunction Status REL2 terminal voltage is below 1.4 V (*) - -
REL2 terminal voltage is above 9 V (*) - -
Detection Time Approximately 1 second Approximately 1 second Approximately 1 second Approximately 1 second
Trip Count 1 trip 1 trip 1 trip 1 trip

HINT: 

Threshold Changes According to BECU Terminal Voltage 

GTY798727Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
*a BECU Terminal Voltage (V)
*b REL1 or REL2 Terminal Voltage (V)
*c Normal Range
*d DTC Detection Range
DTC DETECTION CONDITION COMBINATION TABLE: C13AC

  Vehicle Condition
Pattern 1 Pattern 2
Diagnosis Condition Electric parking brake switch assembly is operated to lock side with power switch off -
Power switch on (IG) -
Malfunction Status Release 1 switch and release 2 switch ON/OFF evaluations do not match
Detection Time Repeats 5 times Repeats 5 times
Trip Count 1 trip 1 trip

HINT: 

If the conditions match either of these patterns, a DTC will be output.