A TPMS (Tire Pressure Monitoring System) teardown is a detailed process of disassembling the components of a tire pressure sensor to gain a deeper understanding of its internal structure and potentially replace the battery. This comprehensive guide will delve into the key components involved, the recommended battery replacement frequency, common issues encountered during the teardown process, and the technical specifications of TPMS sensors.
Key Components Involved in a TPMS Teardown
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Valve Stem: The valve stem is a crucial component that serves as the attachment point between the TPMS sensor and the wheel. It is typically secured to the sensor using a small bolt, measuring approximately 5-7 mm in length. While the valve stem does not directly read any data from the tire, it plays a vital role in transmitting the pressure information from the sensor to the vehicle’s TPMS system.
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Sensor: The sensor is the primary component responsible for measuring the tire pressure. It is typically housed on a microchip and is powered by a battery. The sensor’s dimensions can vary, but a common size is around 25-30 mm in diameter and 10-15 mm in height. The sensor’s accuracy is typically within ±1 psi (±0.07 bar) of the actual tire pressure.
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Battery: The battery used in TPMS sensors is usually a 3-volt CR2032 coin cell, a widely used type in various electronic devices. The battery’s dimensions are approximately 20 mm in diameter and 3.2 mm in height, weighing around 2-3 grams. The battery life can range from 5 to 7 years, depending on factors such as usage patterns and environmental conditions.
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Microchip: The microchip is the electronic brain of the TPMS sensor, containing the circuitry responsible for processing the pressure data and transmitting it to the vehicle’s TPMS system. The microchip is typically a surface-mount device (SMD) with dimensions around 5-10 mm in length and 3-5 mm in width.
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Plastic Case: The plastic case serves as the housing for the TPMS sensor, battery, and other components. It is designed to be sealed and not intended for user serviceability. The case dimensions can vary, but a common size is around 30-40 mm in diameter and 15-20 mm in height. The case material is typically a durable thermoplastic, such as polyamide or polycarbonate, to withstand the harsh environmental conditions encountered in the wheel well.
How Often to Replace Batteries in TPMS Sensors
The batteries in TPMS sensors are designed to last for several years, but their lifespan can be influenced by various factors, such as usage patterns, temperature extremes, and environmental conditions. It is generally recommended to replace the batteries in TPMS sensors every 5 to 7 years or when the vehicle’s TPMS system indicates a low battery warning.
Replacing the battery is a crucial maintenance task, as a dead battery can cause the TPMS system to malfunction, leading to inaccurate tire pressure readings or even a complete system failure. Neglecting battery replacement can result in increased fuel consumption, reduced tire life, and potential safety risks.
Common Issues During a TPMS Teardown
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Dead Battery: A dead battery is the most common issue encountered during a TPMS teardown. As the battery ages, its capacity diminishes, eventually leading to the sensor’s inability to transmit data to the vehicle’s TPMS system.
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Sensor Failure: The sensor itself can fail due to various reasons, such as physical damage, water ingress, or electronic component malfunctions. In such cases, the entire TPMS unit may need to be replaced.
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Water or Moisture Ingress: The TPMS sensor is designed to be weatherproof, but over time, water or moisture can find its way into the plastic case, leading to corrosion and sensor failure. This can be a particular issue in regions with high humidity or frequent exposure to water, such as heavy rain or snow.
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Physical Damage: The TPMS sensor and valve stem can sustain physical damage during tire changes, wheel rotations, or other maintenance activities. This can result in sensor malfunction or even complete failure, requiring replacement of the entire TPMS unit.
Technical Specifications of TPMS Teardown
- Battery Type: CR2032, 3-volt
- Battery Dimensions: Diameter: 20 mm, Height: 3.2 mm, Weight: 2-3 grams
- Sensor Dimensions: Diameter: 25-30 mm, Height: 10-15 mm
- Sensor Accuracy: ±1 psi (±0.07 bar) of the actual tire pressure
- Plastic Case Dimensions: Diameter: 30-40 mm, Height: 15-20 mm
- Plastic Case Material: Thermoplastic, such as polyamide or polycarbonate
- Valve Stem Bolt Length: 5-7 mm
- Tools Required: Multi-valve core tool, smartphone repair tool kit, putty knife, small cutting knives, silicone sealant, solder gun, and solder
References
- https://www.youtube.com/watch?v=zOdpN8FcLPQ
- https://www.youtube.com/watch?v=xnVykoC1820
- https://www.chargerforums.com/threads/tpms-sensor-disassembly-photos.396030/
- https://www.youtube.com/watch?v=avlr4hs7iV8
- https://www.youtube.com/watch?v=e8e043n7OTI