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Summary
  • The tachometer is a component on the dashboard that displays the speed of the engine’s rotating crankshaft.
  • Some vehicles don’t have a tachometer, because it’s not a necessity for the most part.
  • Wiring issues are to blame if the tachometer isn’t functioning.

Every vehicle is designed to ensure that performance-related information is easily accessible to its driver. This is why your dashboard houses different tools to keep you aware of what’s going on under the hood, such as the tachometer or revolution per minute (RPM) gauge. It’s one of the important components that allow you to keep an eye on what your engine is doing.

A Tachometer’s Parts

The tachometer is a gadget on your dashboard that displays the speed of the engine’s rotating crankshaft. It basically tells you how fast your engine is running. It may appear on your digital display, but some vehicles may have an old-fashioned dial normally found next to your speedometer. A tachometer is a standard feature on manual-transmission vehicles, so you can change gears as needed. Take note, however, that some vehicles don’t have a tachometer, because it’s not a totally necessary instrument, even on manual transmission platforms.

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The parts of a tachometer depend greatly on the age and make of your vehicle. Older tachometers were connected to the trigger side of the ignition coil. Others receive their signal from the ignition module or the engine controller (ECM/PCM). Still others may receive information directly from the crankshaft sensor. Many modern instrument clusters are fitted with a small processor and receive engine rpm information on the vehicle network bus. In other words, one size doesn’t fit all when it comes to the tachometer.

modern car tachometer
The tachometer is a gadget on your dashboard that basically tells you how fast your engine is running.

A tachometer isn’t a required device for automatic-transmission vehicles. They’re set up to shift gears on their own. This makes tachometers unnecessary for automatic-transmission vehicles, but some may still have them for engine function monitoring or cosmetic purposes. A tachometer dial generally has numbers etched along its edge to signify your engine’s RPM. The dial may also be color coded with yellow and red ranges. Driving at your tachometer’s red area for long durations may lead to engine failure.

Why Is My Tachometer Not Working?

Is your tachometer or RPM gauge not working? Like any part in your vehicle, it may malfunction or not work at all due to damage and wear. Here are common issues you may encounter with your tachometer:

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tachometer in a car dashboard
Driving at your tachometer’s red area for long durations may lead to engine failure.

Stepper Motor

Some GM vehicles may have a bad stepper motor that drives the tach needle on the instrument cluster board. This is fairly common on some GM vehicles, particularly mid 2000s pickups.

Inaccurate readings

Erratic or inaccurate readings may be caused by wiring complications and electrical interference from other devices. In some cases, the tachometer gauge itself is the cause of the inaccurate readings.

Busted LED screen

For vehicles with tachometers on the digital display, the readings may not show up if the LED screen becomes faulty or broken. Other important information may also be displayed on your LED screen. Replace it as soon as possible, so you can monitor your vehicle’s performance properly and use other interior features that may require a working display.

Tachometer Is Not Responding at All

When you turn on your engine and your tachometer is not responding at all, you need to check if it has become faulty or has wiring issues. If you have a voltmeter, you can use it to check its wires by setting your engine to idle and investigating for any inconsistencies. If readings come back normal, your tachometer may have become busted and requires replacement.

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All of these issues can be determined and resolved with a trip to your mechanic. Some display or tachometer replacements may seem easy enough to do on your own, but it’s best to consult a professional, so that you can make sure this vital tool is properly fixed and precisely calibrated.

About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

File Under : DIY , Interior Tagged With :
Garage Essentials
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Sbongile

Hi my car rev counter is not moving I’m doing chrysler auto and when drive above 100km.its start shaking

Casey Wilson

My 2019 Camaro rpm gauge stop working.. why?

Darren

My car takes about 15 seconds to get past 20mph and my rpm isn’t working

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