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DTC C1A4B: Stop Light Relay Circuit [08/2015 - 08/2019]: Description

The skid control ECU outputs a stop light operation signal to the stop light control ECU. When the skid control ECU detects a malfunction in the stop light circuit, the driving support ECU outputs DTC C1A4B.

DTC Code DTC Detection Condition Trouble Area
C1A4B Either of the following conditions is met:
  • When the engine switch is on (IG), the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is output, the signal is not received at terminal STP2 for 0.3 seconds or more.
  • When the engine switch is on (IG), the IG1 terminal voltage is between 11 and 14 V and the stop light illumination output signal (STPO) is not output, the signals received at terminals STP and STP2 are different for 0.3 seconds or more.
  • Lighting system
  • Vehicle stability control system
  • Harness or connector
  • Stop light control ECU
  • Driving support ECU