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Home >> Toyota >> 2012 >> Prius Four >> Repair and Diagnosis (Single Page) >> Restraints >> Restraints Control Systems >> Pre-Collision System (Except Plug-In) (Diagnostic Codes & Circuit Tests) >> Pre-Collision System >> DTC C1A4B: Stop Light Relay Circuit >> Description
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DTC C1A4B: Stop Light Relay Circuit: Description

The stop light switch assembly outputs a brake pedal operation signal to the driving support ECU. Based on the signal, the driving support ECU cancels cruise control.

DTC No. DTC Detection Condition Trouble Area
C1A4B When the power switch is on (IG), a stop light relay malfunction signal is received from the brake booster with master cylinder (skid control ECU).
  • Lighting system
  • Electronically controlled brake system
  • CAN communication system
  • Driving support ECU
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