1991-1995 Buick Commercial Chassis Speed Sensor Guide
Understanding the signs of a failing vehicle speed sensor and how to choose a replacement for your specialty Buick.
- A failing speed sensor will primarily affect the speedometer, transmission shifting, and cruise control.
- The most common trouble code associated with this failure is P0500.
- For this vehicle, a new aftermarket part is the most practical and available replacement option.
- Replacement is a simple, low-cost job that is feasible for a DIY mechanic with basic tools.
Is My Speed Sensor Failing?
A bad speed sensor on the Buick Commercial Chassis, which often uses a GM 4L60 or 4L60E transmission, will cause noticeable problems. Because the sensor provides data for multiple systems, its failure can appear in several ways. You are the best judge of how your vehicle normally drives, so be aware of any new or unusual behavior.
Common Symptoms of a Bad Speed Sensor:
- Erratic or Dead Speedometer: The most obvious sign is a speedometer that jumps around, reads incorrectly, or doesn't move at all.
- Harsh or Incorrect Shifting: The automatic transmission may shift hard, delay shifts, or get stuck in one gear because it doesn't know how fast the vehicle is moving.
- Cruise Control Not Working: The cruise control system relies on a steady speed signal to function. If the signal is lost, the cruise control will not engage.
- Check Engine Light: The vehicle's computer will often trigger a Check Engine Light and store a trouble code like P0500 when it detects a problem with the VSS signal.
Don't Confuse VSS with ABS Sensors
Your vehicle has two types of speed sensors. The main Vehicle Speed Sensor (VSS) is on the transmission and controls the speedometer and shifting. There are also individual ABS wheel speed sensors at the wheels that are part of the anti-lock brake system. This guide focuses on the main VSS on the transmission.
Choosing the Right Aftermarket Speed Sensor
For a vehicle from the early 1990s, finding a new original equipment (OEM) speed sensor from GM is highly unlikely. The market is now served by aftermarket manufacturers. The "Replacement" brand category covers parts that are designed to be direct, factory-fit replacements that meet or exceed original specifications.
When shopping for a new aftermarket speed sensor, quality is key. Look for brands that have a long history in the aftermarket, as they have experience engineering parts for specific vehicle platforms like your GM D-body chassis. A quality replacement sensor will use durable materials and OE-style sealed connectors to protect against moisture and dirt, ensuring a long service life.
Pro Tip: Before ordering, it's a good idea to visually inspect the sensor on your transmission. Check the connector shape and the number of pins to ensure the new part is an exact match.
Cost of Replacing a 1991-1995 Buick Commercial Chassis Speed Sensor
Replacing the speed sensor is one of the more affordable repairs you can make. The part itself is not expensive, and if you have it done at a shop, the labor is minimal as the sensor is usually easy to access on the outside of the transmission.
| Part/Service | Estimated Cost |
|---|---|
| New Aftermarket Speed Sensor | $38.48 - $56.59 |
| Shop Labor | $50 - $100 |
| Total Estimated Cost (Shop) | $88 - $157 |
Frequently Asked Questions
Where is the speed sensor located on my Buick Commercial Chassis?
The main vehicle speed sensor (VSS) is located on the tail-shaft housing of the automatic transmission. You will need to safely raise the vehicle to access it from underneath. It is typically held in place by a single bolt and has an electrical connector attached.
Can I replace the speed sensor myself?
Yes, this is a very DIY-friendly repair for most home mechanics. The job requires basic hand tools, a floor jack, and jack stands for safety. The process involves disconnecting the electrical connector, removing one bolt, and swapping the old sensor for the new one. The estimated time is under an hour.
Are there any recalls for this part?
No, there are no open recalls from the NHTSA for the vehicle speed sensor on the 1991-1995 Buick Commercial Chassis or its sister vehicles like the Roadmaster.
Will a bad speed sensor prevent my car from starting?
No, a bad speed sensor will not prevent the engine from starting. However, it can cause significant drivability issues, such as being stuck in a single gear, which may make the vehicle difficult to operate.
Technical Specifications
Typically a 2-pin magnetic sensor that mounts on the transmission tail-shaft housing. Generates an AC signal that corresponds to vehicle speed.
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Buick Commercial Chassis: