P1574

Circuit Description

The Brake Lamp Switch is normally open switch. When the brake lamp switch is closed, the TAC module senses ignition voltage on the brake switch signal circuit. The PCM compares this signal to the signal received from the other brake switches. If these switches do not agree this DTC will set.

Conditions for Running the DTC

^ The engine speed is greater than 700 RPM.
^ The engine operates longer than 2 second.
^ The wheel speed must be greater than 30 MPH in order to enable the diagnostic. The diagnostic will disable when the wheel speed is below 10 MPH.
^ The vehicle speed is decreasing at a rate greater than 10.4 MPH over a one second period.

Conditions for Setting the DTC

^ The PCM senses this switch is not toggling as compared with other brake switch inputs.
^ The condition is present for 20 accel/decel cycles.

Action Taken When the DTC Sets

^ The PCM will not illuminate the Malfunction Indicator Lamp (MIL).
^ The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

^ A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ DTC can be cleared by using the scan tool Clear Info function.

Diagnostic Aids

Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing/replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion. In order to adjust the Brake Lamp Switch perform the following:

1. With the brake pedal depressed, insert the Brake Lamp Switch into the retainer until the switch body seats in the retainer. You can hear clicks as you push the threaded portion of the switch through the retainer.
2. Slowly pull the brake pedal fully rearward against the stop until you can no longer hear the clicks.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

2. This step determines if the fault is present.
11. This is step verifies that the Brake switch is functioning properly.
20. Check for a short to ground between the fuse and the Stop Lamp switch and between the Stop Lamp switch and the TAC module.
15. This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.