P0571
DTC P0571
Circuit Description
When the brake pedal is depressed, the stop light switch sends a signal to the engine control module (ECM). When the ECM receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition occurs when voltage is applied to ECM connector A50 terminal 36. When the brake is applied, voltage is normally applied to terminal 36 of the ECM through the STOP fuse and the stop light switch, and the ECM turns the cruise control off.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0571 Brake Switch Circuit 1
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
Voltage at terminals 35 and 36 of the ECM are less than 1 volt for 0.5 second or more.
Action Taken When the DTC Sets
* The ECM illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs with the fault active.
* The ECM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.
Conditions for Clearing the MIL/DTC
* The MIL turns OFF after 3 consecutively passing trips without a fault present.
* A History DTC clears after 40 consecutive warm-up cycles without a fault.
Diagnostic Aids
A scan tool should indicate the state of the stop light switch.
An intermittent malfunction may be caused by a fault in the stop light electrical circuit. Inspect the wiring harness and the components for any of the following conditions:
* Any backed-out terminals
* Any improper mating of terminals
* Any broken electrical connector locks
* Any improperly formed or damaged terminals
* Any faulty terminal-to-wire connections
* Any physical damage to the wiring harness
* A broken wire inside the insulation
* Any corrosion of the electrical connections, the splices, or the terminals
Repair any electrical circuit faults that were found. Refer to Wiring Repairs (Wiring Repairs).
