Modern vehicles come with many different sensors that work together with the mechanics of your vehicle’s system in order to ensure it is running smoothly and as it should. Sensors are typically read by your PCM, or computer, which relays the message to the necessary parts so that they perform as needed. One such sensor is your vehicle speed sensor.

What exactly is a speed sensor and what is its purpose? This article will help shed some light on the vehicle speed sensor purpose and importance to your vehicle’s ability to function properly.

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How Does a Vehicle Speed Sensor Work?

Conventional speedometers are operated by the use of a drive cable tucked away within housing. The cable would be spun via a gear located towards the rear of the vehicle’s transmission. When replacing your tires, if you chose a different size, adjustments to the gear size could be made to compensate. A vehicle speed sensor replaces that old school speedometer system.

The vehicle speed sensor is in the tail housing if your vehicle is a rear wheel drive. For front wheel drive applications, the vehicle speed sensor is likely to be spotted near your drive axles on the top of your transmission. The sensor will have a plug in electrical connector. It uses the wiring to transmit a signal to the computer as it rotates. This information is useful to calculate your speed. The signal also tells your vehicle if there is a need to adjust your shift levels or transmission speed.

Your vehicle speed sensor is also responsible for keeping track of the distance you travel to relay to your odometer to show your elapsed mileage. This particular sensor is magnetic. It also sends information regarding when to auto-lock doors in some vehicles and certain handling and stabilizing technologies found in newer vehicles. This includes information your anti-locking brake system needs to function correctly.

How to Tell When Your Vehicle Speed Sensor Needs a Replacement

Since your speed sensor is integral in many functions, it can cause a wide array of issues. This makes it difficult to pinpoint that your speed sensor is the culprit and not one of the components that rely on information sent from it. Thus, you can see how necessary it is to keep a functioning sensor on your vehicle. Here are some common issues you may experience if your sensor is faulty:

  • Before your vehicle shifts gears, you may experience unusually high revving in your transmission;
  • Your vehicle may take too long to switch into overdrive or it may never allow itself to reach it at all;
  • The brake pedal may feel stiff when coasting;
  • Also, the speedometer may cease functioning or it may begin to behave erratically;
  • When you accelerate, you may notice your check engine light will pop on and then disappear when you coast or slow down;
  • Another sign of a faulty speed sensor is if your overdrive light blinks for no reason;
  • High fuel consumption.

These are common indications you may need to replace your vehicle speed sensor. Most people opt for an OEM sensor. However, if you own an older vehicle and want to upgrade to a more modern speed sensor there are options you can utilize. Though, you will need to have a good understanding of wiring and electricity and do not mind a bit of mod work.

General Specifications

  • Records the speed your crankshaft spins;
  • Helps monitor and adjust many computer assisted systems such as ABS and shift levels;
  • Sits in the tail housing of a rear wheel drive or is on the differential housing for front wheel drives;
  • Replaces old cable driven speedometers;
  • Typically secured by a 10 mm bolt;
  • Has a single plug in electrical pigtail.

PROs and CONs of Replacing or Upgrading a Vehicle Speed Sensor

PROs: 

  • Allows your vehicle and its systems to run properly;
  • Is easy to replace;
  • Is inexpensive to replace.

CONs: 

  • If you upgrade your older vehicle, you need a good understanding of electrical and mechanical systems;
  • Upgrades can be difficult and expensive to install;
  • Limited to certain types up sensor upgrades depending on what system your vehicle uses (cable, 2 wire, 3 wire);
  • When any sensor goes bad it is hard to diagnose because it links to so many other components. Thus, you may suspect a component over the sensor.

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3 Top Models of Vehicle Speed Sensors

1. Duralast Vehicle/Transmission Speed Sensor: Duralast is a top name in advanced vehicle electronics. Manufactured by Wells Vehicle Electronics, their products are built to last and outperform OEM parts. They are still built to OEM specifications so that install is quick and easy. Also, you are able to perfectly match the part to your vehicle. Customers love everything about the easy install and reliability of their products.

2. Delphi SS10568 – Automatic Transmission Speed Sensor: Designed to be compatible with any control module, Delphi boasts a clean signal. Customers agree that Delphi delivers a high efficiency part that out performs other brands at a low price.

3. Standard Motor Products SC105T Transmission Speed Sensor: Standard may not be a name brand favorite. But when you just need something to get you by, they are there to help. Offering direct fit parts at an affordable price, many customers appreciate being able to grab something quick and easy to get by for a while.

Wrapping Up

Knowing how your vehicle speed sensor ties into so many systems and keeps your vehicle driving properly really reiterates this single sensor’s importance. If you suspect a component is failing but know that it gets it information from the sensor, you now know to check the speed sensor first to possibly save you money on an unnecessary repair. Keep your sensor in working order to get the most out of your fuel economy, transmission, and to be safer on the road.

What signs did you see when you needed a vehicle speed sensor replacement? Was it a difficult part to find and replace? Have you ever modded a vehicle to use a sensor that was not OEM for your vehicle? How difficult was it to do? Feel free to share any comments or experiences below for others.

Images from depositphotos.com.

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