GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2007 🢒 Vivant 🢒 HVAC 🢒 HVAC - Automatic 🢒 DTC 024

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 024: Vehicle Speed Sensor (VSS) Circuit

Circuit/System Description

The vehicle speed information is provided to the engine control module (ECM) by the vehicle speed sensor (VSS). The VSS is a permanent magnet generator that is mounted to the transmission and produces a pulsing voltage. The AC voltage amplitude and frequency increases with vehicle speed. The ECM converts the pulsing voltage into km/h (mph). The ECM supplies the VSS signal to the following components:

    • The instrument panel for speedometer and odometer operation
    • The cruise control module
    • The multi-function alarm module

Conditions for Setting the DTC
    • DTC 034 is not set.
    • The engine speed is between 2,000-5,000 RPM.
    • The VSS indicates a speed less than 6 km/h (4 mph).
    • The manifold absolute pressure (MAP) sensor signal indicates less than 24 kPa (3.4 psi).
    • The DTC runs continously once the above conditions are met for 2 seconds.

Diagnostic Aids
    • Ensure the VSS is correctly torqued to the transmission housing.
    • This DTC may be set due to an instrument panel (IP) cluster condition.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls 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
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification
  1. Raise the drive wheels.

    2. Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

  2. Support the lower control arms so that the drive axles are in a horizontal position.
  3. Start and idle the engine.
  4. Engage the transmission into 2nd gear.
  5. Observe the VSS parameter with a scan tool.

The following should display a vehicle speed once the drive wheels are at a speed above 8 km/h (5 mph):

    • The VSS parameter
    • The speedometer

Circuit/System Testing
  1. Ignition OFF, disconnect the harness connector at the VSS.

    2. Important: The test lamp is used to load the circuit and may not illuminate.

  2. Connect a test lamp between the ignition 1 voltage circuit of the VSS and ground.
  3. Ignition ON, load test for battery voltage between the ignition voltage circuit and ground.
    4. ⇒If less than B+, repair the ignition voltage circuit for a short to ground, or an open/high resistance.
  4. Ignition ON, test for less than 0.1 volts between the VSS ground circuit and the negative terminal of the battery.
    5. ⇒If greater than 0.1 volts repair the ground circuit for an open/high resistance.
  5. Ignition ON, test for 9-11 volts between the signal circuit of the VSS and the negative terminal of the battery.
    6. ⇒If less than 9 volts test the VSS signal circuit for a short to ground or an open/high resistance. If the circuit/connections test normal, replace the ECM.
    ⇒If greater than 11 volts test the VSS signal circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
  6. If the voltage is within the specified range replace the VSS.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module replacement, setup, and programming.