Vehicle Speed (VSS) Sensor

WARNING: This page is about a different car, the 2002 Ford Econoline. However, it is still accessible from the selected car via links, so may be relevant.

The source of vehicle speed (VSS) is model dependent. Possible sources of vehicle speed input are anti-lock brake sensor (ABS), a gear-driven vehicle speed sensor (VSS), or an output shaft speed sensor (OSS). The VSS signal is either an A/C signal whose frequency changes with speed, or an SCP data message depending on the source. Some applications will have both. The vehicle speed signal is an input to various vehicle subsystems such as the powertrain control module (PCM), instrument cluster (speedometer and odometer), speed control system, etc. The vehicle speed source must be operational to enter output state control (OSC) mode for diagnostics.

Regardless of the type of vehicle speed system, the PCM always uses the OSS for transmission and engine control.

NOTE: Do not take any short cuts or assume that critical checks or adjustments have already been made.

Follow the procedures as written to avoid missing critical components or steps.

To properly diagnose a concern have the following publications available:

Transmission Reference Manual.
SELF-DIAGNOSTICS - EEC-V - GASOLINE & NGV article.
TSBs and OASIS Messages.
Wiring Diagram.

These publications provide the information required when diagnosing transmission concerns.

Use the Diagnostic Flow Chart as a guide and follow the steps as indicated.