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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Cobalt 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 DTC P1574

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1574 00 : Stop Lamp Switch Circuit

Circuit/System Description

The cruise release switch is a normally closed switch. The stop lamp switch signal circuit is a normally open switch. When the brake pedal is released, the engine control module (ECM) detects a high voltage signal on the torque converter clutch (TCC) brake switch/cruise control release signal circuit and a low signal voltage signal on the stop lamp switch signal circuit.

Conditions for Running the DTC
    •  DTCs P0502, P0503, P0719, and P0724 are not set.
    • The engine speed is greater than 700 RPM.
    • The traction control system or the antilock brake system are not active and have not failed.
    • The vehicle speed is greater than 48 km/h (30 mph) in order to enable the diagnostic.
    •  The diagnostic will disable when the wheel speed is less than 16 km/h (10 mph).

Conditions for Setting the DTC
    • The vehicle speed decreases by at least 4.2 km/h (2.6 mph) within 0.25 seconds.
    • The ECM detects a TCC brake transition.
    • The ECM does not detect a stop lamp switch transition.

Action Taken When the DTC Sets
    • The ECM stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
    • The Cruise Control System is disabled.

Conditions for Clearing the DTC
    • The history DTC clears after 40 malfunction free warm-up cycles.
    • The DTC becomes history when the conditions for setting the DTC are no longer present.
    • The ECM receives the clear code command from the scan tool.

Diagnostic Aids

In order to avoid a misdiagnosis, perform the following:

    • Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation .
    • Inspect for proper adjustment of the stop lamps. Refer to Stop Lamp Switch Adjustment .
    • For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

Ignition ON, observe the Stop Lamp Pedal Switch parameter in the ECM while applying and releasing the brake pedal. The reading should change between Applied/Released, and all brake lights should turn on and off accordingly.

Circuit/System Testing

Ignition ON, observe the Stop Lamp Pedal Switch parameter.

⇒If the parameter reads Applied, refer to Stop Lamps Always On . If the stop lamps operate normal, replace the ECM.
⇒If the parameter reads Released, test the stop lamp switch signal circuit for an open/high resistance or short to ground. If circuit tests normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM module replacement, setup, and programming