Vital Signs

Having Proper Instrumentation Can Make All the Difference in the World

By Jay Kopycinski

All 4x4s come with idiot lights, those bright-red or amber lights with symbols that illuminate on the dash should something critical happen to the engine or drivetrain. However, by the time those warning lights alert you to a problem, irreparable damage may have already been done to your expensive powerplant. Those indicators simply give no advance warning of impending breakdown or problems before they finally alert you at some predesignated trip point.

Along with simple warning lights, many vehicles come equipped with factory gauges to monitor some basic functions, typically oil pressure and water temperature, and possibly battery or charging voltage. The real advantage of gauges over simpler warning lights is that you can watch meter movement trends over time to monitor the behavior of your vehicle and get more advance warning of possible problems or changes in performance.

However, many stock gauges lack sufficient accuracy or gauge increments to provide reliable, absolute measurements of vital engine functions. Gross markings are often used, and the wide spacing in marking points on the face of the gauge prevents precise determination of true readings. Often the best way to use a factory gauge with minimal markings is simply to determine normal baseline readings and monitor these readings for changes over time.

Luckily, there is a wide array of aftermarket gauges that surpass most stock gauges. These can offer larger face sizes, better visibility, improved accuracy, and greater movement reliability under harsh conditions. Along with these benefits comes the ability to monitor many more functions, including such characteristics as transmission fluid temperature, alternator charging current, air/fuel ratio, intake vacuum, turbo boost, exhaust temperature, fuel pressure, and so on. You can keep adding on until you run out of dash space.

Gauge systems can typically be broken into three basic components: the sender, the harness, and the gauge itself. Gauges such as a voltmeter, fuel level monitor, and tachometer usually require no added sending components, while gauges that monitor such values as pressure or temperature require a sending unit located at the monitor source to sense the value of interest.

A voltmeter is simply wired to whatever monitor point is desired on the vehicle. This may be near the alternator, or it may be further down the length of a harness to monitor voltage drop in the vehicle system. Fuel gauges get their signal from the fuel level sender in the gas tank. Basically, this is a device with a small float on the end of a wire arm. As the fuel level changes, the float moves up or down. The float arm actuates a variable resistance wire within the fuel sender. The gauge then reads this value and displays the fuel level appropriately. Fuel level senders can vary among vehicle manufacturers, so when purchasing an aftermarket gauge, be sure to purchase one matched to your vehicle make.

Tachometers are available in a wide array of styles and sizes. There are basic units that simply display engine rpm, and there are very sophisticated, programmable ones that can provide shift point notification and record various engine speed functions. Tachometers usually require no additional sending unit and are wired directly to the ignition coil or to a similar node in the ignition circuitry.

Gauges that monitor temperature or pressure are commonly available in two varieties: mechanical and electrical. Mechanical gauges usually have a direct means of transferring the sensed parameter to the dash area. For example, oil pressure gauges carry oil from the engine through a small plastic tube to the back of the gauge. Mechanical temperature gauges have a capillary tube that runs from the temperature source to the gauge.

Electrical gauges use a local sending unit to measure the parameter under scrutiny and convert the measurement to an electrical signal that is fed via wire to the meter in the gauge cluster. This type of gauge is typically easier to install and route, since only a set of wires needs to be used. Also, no engine fluids need to enter the engine compartment with this kind of gauge.

Along with the sender or monitoring connections on the back of the gauge, there are typically ground and lighting connections. To make sure the gauges are illuminated at night, simply hook all the lighting connections on the gauges together and then to the original dash lighting wire.

To get an idea of the gauges available and what is involved in installing them, we contacted Nordskog Performance Products. Nordskog has been building U.S.-made gauges for the auto and marine markets for a number of years. The company manufactures both digital and analog gauges in several sizes to suit almost any application or visibility requirement.

The gauges we used for our install came from Nordskog's Pro Series Analog Gauge line. These are large, 2-5/8-inch gauges that are controlled by microprocessors and offer a wide, 270-degree needle sweep. The gauge needle is driven by a stepper motor movement to provide rock-steady needle position and does not twitch under heavy vibration conditions. Illumination for dim conditions is provided by the LED through dial lighting. Also, the gauges are protected by a lifetime warranty.

Another feature of the Nordskog Pro Series gauges is that the company includes either a pushbutton switch on the face that allows the driver to recall the highest gauge reading or a user-programmable warning LED on the bottom face of the gauge. The gauges also feature a 2-amp-capable output to drive warning lights or buzzers.

Aftermarket gauges can be installed in a number of ways. For a custom vehicle or one where the dash panel will be modified, aftermarket gauges can simply be mounted in a plastic, steel, or aluminum panel. If you are adding them onto a stock dash array, aftermarket gauges can be placed in mounting cups and bolted almost anywhere in the vehicle interior. There are also replacement windshield pillars for many vehicles that offer mounting cups for as many as three small gauges.

There are plenty of high-quality gauge options to supplement what the factory gave you. With the parts available on the market, the sky is the limit as to what you can monitor for your engine application.