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How Grads of Auto Mechanic Programs Can Tackle a Defective Tachometer

Published on March 15, 2018 by in Blog

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Usually situated on a car’s dashboard next to the speedometer, tachometers are useful little devices that measure the revolutions per minute (RPM) of an engine’s crankshaft. Why is knowing the RPM of an engine important? If a car’s engine runs at high RPM for too long, then it may overheat, experience insufficient lubrication, or excessive wear and tear. In extreme cases, the engine can even fail!
Depending on the information displayed on a tachometer, drivers can know, for example, if they may need to shift gears or if their vehicle’s engine is struggling across a certain terrain and may need some time to cool down. Tachometers can also indicate if there might be an engine problem.

Tachometers can be either analogue or digital and there are a few mechanical and electrical reasons why they may malfunction. The good news is that defective tachometers are one of the simplest car problems to solve! Keep reading to find out how you can tackle a tachometer repair after your auto mechanic training.

A Blown Fuse Is One of the First Problems to Check For

One of the possible reasons a vehicle’s tachometer may not be working is because of a blown fuse. A blown tachometer fuse essentially has the same effect as a blown out light bulb: it stops fulfilling its function. You can determine if a blown fuse is the cause of the problem by examining the car’s fuse box to see if the tachometer fuse is in working condition. If you find that there is black discoloration on the fuse along with a break in its metal strip, then this means that it’s blown and warrants replacement.

Grads of Auto Mechanic Programs Know Faulty Wiring Can Cause Erratic Tachometer Readings

Graduates of auto mechanic programs know that if a tachometer is displaying erratic readings, then there is usually a problem with its wiring. This is an important problem to address because a pinched or shorted wire could potentially lead to burning out a car’s entire ignition module!

Tachometers typically use four wires and all of these need to be checked to make sure none of them are corroded, loose, or otherwise damaged. It’s crucial to trace them all the way from the dashboard’s display panel to the various places to which they connect to see if any need to be replaced or reconnected.

A good way to figure out in advance if a tachometer isn’t working due to wiring problems is to install and test a working replacement unit. If this unit doesn’t work, then you should look for a problem with the wiring. If it does work, however, then you know to troubleshoot elsewhere.

Unusual Tachometer Readings May Warrant a Calibration Adjustment

A tachometer may also just be poorly calibrated. Professionals with car mechanic training can identify a poorly calibrated tachometer if its RPM readings don’t coincide with the motor’s activity. For example, they may be unusually low or unusually high. In this case, the calibration simply needs to be reset.

Unusually high RPM readings may indicate a poorly calibrated tachometer

Unusually high RPM readings may indicate a poorly calibrated tachometer

As far as tachometer calibration goes, it always needs to be reset if a vehicle’s engine is swapped for another one with a different amount of cylinders. Keeping the same calibration in this case would result in inaccurate readings.

LED Display Malfunctions Can Impede the Proper Functioning of Digital Tachometers

Digital tachometers may be susceptible to malfunctioning due to an LED display issue. Over time, LED displays may get damaged and not display information correctly or not light up at all. In this case, the solution is really easy! Simply replacing the display should do the trick. Sometimes it’s possible to check if just one burned out LED light is causing this malfunction, in which case just the one bulb may need to be replaced.

Digital tachometers may become defective due to a faulty LED display

Digital tachometers may become defective due to a faulty LED display

If none of the above solutions end up fixing a defective tachometer, then the remaining solution is to replace the device itself.

Are you interested in becoming an auto mechanic?

Contact CATI to inquire about our training for mechanics!

 
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