Understanding dashboard indicators
Q: I just bought a nice used car for my 16-year-old daughter to drive. Among all the care and usage recommendations I have given her, the one thing she’s most perplexed about are the gauges. Can you please explain them and their importance? Also, any other tips for a new driver to keep her safe and the car in good condition? Thanks! —Anita P.
A: Sure! Many vehicles employ instrumentation beyond just vehicle speed and fuel level. Let’s look at some of them.
— Tachometer: This displays engine rotational speed. Most engines idle at perhaps 600-700 revolutions per minute (RPM) and have a maximum of maybe 5,000-7,000 RPM. An automatic transmission will typically choose an appropriate gear that best meets power requirements while minimizing fuel use. Higher RPM delivers more power, lower RPM promotes fuel economy. It’s prudent in most cases to run at the lowest RPM possible that delivers needed performance.
— Temperature (thermometer symbol): This gauge spans from perhaps 100-260 degrees F. The normal operating temperature of most engines is 195 F, and the engine should warm up to this level within a few minutes of driving. Temperature may climb somewhat in traffic between cooling fan cycles, or climbing long grades. A reading of 225 F would catch my attention, and if it drops back down after a given condition, it’s not a concern. Above 240 is of high concern, and damage may occur at 260 F. One should keep in mind that overheating an engine can be destructive, and should be avoided at all costs.
— Oil Pressure (oil can symbol): Like blood pressure, this metric is vitally important, but in this case a higher reading is better! Typical readings vary from perhaps 15-20 PSI (pounds per square inch) at idle to about 40-70 PSI at higher engine speeds. Pressure is typically higher when the oil is cool/thick and drops somewhat when warm/hot. If the engine is filled to the proper level and oil is checked and changed regularly, an oil pressure fault (low or 0) is incredibly rare.
— Voltage (battery symbol): This displays the status of the charging system/battery team, and higher is better — to a point. Key-on/ engine-off, one will see about 12.6 volts, a charged and static battery. A typical running voltage is 14.5 volts (charging is ongoing and successful). At idle with many accessories functioning, this may dip a bit. The most likely fault one might see is voltage dropping to just battery (12ish) while driving (charging is not occurring). Head for home right away with reduced accessories used!
How often should gauges be checked? Ideally a quick visual sweep of all gauges every few moments is best. Or at minimum, an occasional peek when climbing hills (temperature). Some vehicles (I wish all) employ a “Check Gauges” light or tone when something is amiss, and others employ just red warning lights in lieu of gauges, which is unfortunately information too little, too late.
Also, I’d recommend: Apply the parking brake every time you park, before placing transmission in park. Renew brake fluid, coolant, belts and hoses every four to five years. Consider a sun windshield shade to protect the vinyl instrument panel. Clean and wax paint every six months, and keep seat seams free of sand/debris.