P1574 (TCM With RPO Code L61, MN5)

DTC P1574 (TCM w/L61w/MN5)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Strategy Based Diagnosis
* Diagnostic Procedure Instructions

DTC Descriptor
DTC P1574
- Stop Lamp Switch Circuit

Diagnostic Fault Information






Circuit/System Description

The stoplamp switch is used to sense the action of the driver application of the brake pedal. The stoplamp switch will apply battery voltage to the park/stoplamp signal voltage supply circuit to illuminate the stop lamps and the center high mounted stop lamp (CHMSL). The stoplamp switch also sends a signal to the Transmission control module (TCM) as well to indicate the application of the brake pedal.

Conditions for Running the DTC

* The ignition is ON.
* Battery voltage is greater than 11.5 volts.

Conditions for Setting the DTC

The TCM detects a short to ground, short to voltage, or open on the stop lamp switch signal circuit when the brakes are applied.

Action Taken When the DTC Sets

* The TCM stores the DTC to memory.
* The TCM will record the operating conditions at the time the diagnostic failed. The TCM stores this information in Failure Records.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* You issue a scan tool CLEAR DTCs command.
* A history DTC will clear once 40 malfunction-free ignition cycles have occurred.

Circuit/System Testing

1. Perform the stoplamp switch adjustment, refer to Stop Lamp Switch Adjustment, clear all DTCs, and operate the vehicle within the Conditions for Running the DTC.

• If DTC P1574 resets as current, test the stop lamp switch signal circuit for a short to ground, short to voltage, or open.

2. If circuits test OK, replace the TCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Control Module References for TCM replacement, setup, and programming. Programming and Relearning
* Stop Lamp Switch Adjustment