Locating the Transmission Position Sensor on a 2009 Smart Fortwo
The transmission position sensor, also sometimes called a neutral safety switch or gear position sensor, plays a critical role in the operation of your 2009 Smart Fortwo. This sensor communicates the gear selector’s position to the car’s computer, allowing it to start, shift gears correctly, and prevent starting in gear. Locating this sensor can be tricky, but understanding its general location and the steps involved in accessing it will greatly aid in any maintenance or repair work. Knowing this information will save you time and potentially money on mechanic fees. Keep reading to find out exactly where to find it.
Understanding the Transmission Position Sensor in Your Smart Car
Before diving into the location, let’s clarify what the transmission position sensor does. It’s essentially an electrical switch that signals to the car’s computer which gear is selected (Park, Reverse, Neutral, Drive, etc.); This information is vital for several functions:
- Starting the Engine: The car will only start in Park or Neutral;
- Gear Selection: The computer uses the sensor’s input to control the automatic transmission’s shifting.
- Reverse Lights: The sensor activates the reverse lights when the car is in Reverse.
Where to Locate the Sensor: A Step-by-Step Guide
The transmission position sensor in a 2009 Smart Fortwo is typically located on the exterior of the transmission housing. It’s generally accessible from underneath the vehicle. Here’s a general guide to finding it:
- Safety First: Always use proper safety precautions when working under a vehicle. Use jack stands to support the car after lifting it with a jack. Never rely solely on a jack.
- Locate the Transmission: The transmission is located towards the rear of the vehicle, connected to the engine.
- Look for the Sensor: The sensor is a small, usually black or grey, electrical component mounted on the side or top of the transmission housing. It will have a wiring harness connected to it.
- Follow the Wires: Trace the wiring harness connected to the gear selector lever (inside the car) down towards the transmission. This should lead you directly to the sensor.
Important Note: Due to variations in specific Smart Fortwo models or aftermarket modifications, the exact location might vary slightly. Consulting a repair manual specific to your vehicle is highly recommended.
Visual Aid: What to Look For
The sensor will typically have a connector with several wires leading to it. It’s often held in place by bolts or screws; Refer to a repair manual for a diagram specific to your 2009 Smart Fortwo.
Troubleshooting Transmission Position Sensor Issues
If you suspect a faulty transmission position sensor, you might experience the following symptoms:
- The car won’t start.
- The car starts in gear other than Park or Neutral.
- Erratic shifting.
- Reverse lights not working.
- Check Engine Light illuminated.
If you experience any of these issues, consider having the sensor tested by a qualified mechanic. A diagnostic scan can often pinpoint the problem.
Comparison of Sensor Replacement Options
| Option | Pros | Cons | Approximate Cost |
|---|---|---|---|
| DIY Replacement | Lower cost, learn about your car. | Requires tools and mechanical knowledge, potential for errors. | Cost of the sensor (approx. $50-$150) |
| Professional Replacement | Guaranteed work, proper diagnosis. | Higher cost. | Sensor cost + Labor (approx. $150-$400) |
FAQ: Common Questions About the 2009 Smart Fortwo Transmission Position Sensor
What tools do I need to replace the sensor?
You’ll typically need a socket set, wrench set, jack, jack stands, and potentially a multimeter for testing.
Can I test the sensor myself?
Yes, using a multimeter to check for continuity and resistance in different gear positions. Refer to a repair manual for specific testing procedures.
How often should I replace the sensor?
The sensor should only be replaced if it fails. There’s no scheduled maintenance interval.
Where can I buy a replacement sensor?
Auto parts stores, online retailers, and your local Smart car dealership.
Is it difficult to replace the sensor?
The difficulty depends on your mechanical skills. If you’re comfortable working on cars, it’s a manageable task. If not, it’s best to consult a professional.
