DTC P0703-12: Brake Switch "B" Circuit Short to Battery [10/2022 - ]: Description

WARNING: This page is about a different car, the 2025 Lexus RX 350, 2024 Lexus RX 350, and 2023 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.

The purpose of the stop light switch signal circuit is to prevent the engine from stalling when the brakes are suddenly applied while driving in the lock-up condition.

When the brake pedal is depressed, the stop light switch assembly sends a signal to the ECM. The ECM then cancels the operation of the lock-up clutch while braking is in progress.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	DTC Output from	Priority	Note
P0703-12	Brake Switch "B" Circuit Short to Battery	All of the following conditions are met (2-trip detection logic): The ignition switch is ON. The battery voltage is 8 V or more. The stop light switch remains ON while the vehicle is driven in a GO (30 km/h (19 mph) or more) and STOP (less than 3 km/h (2 mph)) pattern 5 times.	Stop light switch assembly Short in stop light switch signal circuit ECM	Comes on	Transmission	A	SAE Code: P0724