GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Epica 🢒 DTC 🢒 DTC P0501

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 provide an overview of each diagnostic category.

DTC Descriptor

DTC P0501: Vehicle Speed Sensor (VSS) Performance

Circuit/System Description

The transmission control module (TCM) provides the engine control module (ECM) vehicle speed information through the high-speed communications on the controller area network (CAN). Vehicle speed is produced by the AC current generated through the transmission output shaft speed (OSS) sensor as the output shaft rotates. The ECM continuously monitors the vehicle speed signal supplied by the TCM.

Conditions for Running the DTC
    • The engine is running.
    • The vehicle speed is 0 km/h (0 mph) for 25 seconds.
    • The engine speed is more than 2500 RPM.
    • The ignition 1 voltage is more than 10 volts.
    • The mass air flow (MAF) is more than 18 g/s.
    • DTC P0501 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects that the vehicle speed is 0 km/h (0 mph) for more than 26 seconds.

Action Taken When the DTC Sets

DTC P0501 is a Type B DTC

Conditions for Clearing the DTC

DTC P0501 is a Type B DTC

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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

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 scan tool VSS parameter. The following should display a vehicle speed once the drive wheels are at a speed above 8 km/h (5 mph):
    6. • The VSS parameter
    • The speedometer
  6. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Ignition ON, verify there are no TCM DTCs set.
    2. ⇒If TCM DTCs are set refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
  2. Ignition OFF, test the CAN communication circuits between the ECM and the TCM for an open, short to ground, or a short to voltage.
  3. If all circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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