DTC P0571 Stop Light Switch Circuit Malfunction: Description

WARNING: This page is about a different car, the 2007 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.

The cruise control system cancels cruising when the ECM detects that the brake pedal is depressed while cruise control driving. The stop light switch assembly sends signals to the ECM according to the brake pedal conditions. When the brake pedal is free, terminal ST1- is the positive (+) battery voltage, and terminal STP voltage is below 1 V. While depressing the brake pedal, terminal ST1- is below 1 V, and STP is positive (+) battery voltage. Under braking, the ECM cancels cruise control as one of the manual cancel functions.

The ECM outputs this trouble code when the voltage of terminals ST1- and STP are both below 1 V for 0.5 seconds or more at the same moment.

The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit.

DTC DETECTION SPECIFIED CONDITION

DTC No.	DTC Detected Conditions	Trouble Areas
P0571	ECM detects a malfunction of the stop light switch circuit under both of the following conditions. Voltage of terminal STP is below 1 V for 0.5 seconds or more. Voltage of terminal ST1- is below 1 V for 0.5 seconds or more.	Stop light switch assembly Stop light switch assembly circuit ECM