How to Install a Car Volt Amp Gauge

When you think about the number of sensors that your engine has, it seems like there is an endless amount of gauges that can be installed to monitor their readings. Some of these readings are important, but many of them are simple inputs to the vehicle's computer. The most common gauges on today's vehicles are the speedometer, tachometer, fuel gauge, and temperature gauge. Besides having these gauges, your car will have a number of warning lights that will illuminate if there are problems with those systems. One gauge that is missing in most vehicles is the charging, or voltage, gauge. With a little information you can easily add a voltage gauge to your vehicle.

Part 1 of 2: The purpose of a voltage gauge

Most vehicles built today come with a warning light on the dash that looks like a battery. When that light illuminates, it typically means that there is not enough voltage in the vehicle's electrical system. Most of the time this is due to a failure in your vehicle's alternator. The downfall of this warning light is that, when it comes on, the voltage in the system is very low - and if the battery becomes low enough, the vehicle will end up stalling.

Installing a voltage gauge will allow you to see changes in the charging system well before it becomes a serious problem. Having this gauge will make it much easier to decide whether it is time to pull your vehicle off of the road, or if you can make it to where you are going.

Part 2 of 2: Installing the gauge

Materials Needed

Step 1: Park your vehicle and apply the parking brake. Your parking brake should be a pedal or a hand brake. If it's a pedal, push it down until you feel the brake engage. If it's a hand brake, push the button in and pull up on the lever.

Step 2: Install the memory saver per the manufacturer’s instructions.

Step 3: Open the hood. Release the latch inside the car. Stand in front of the car and lift up the hood.

nagative cable removed and away from battery

Step 4: Disconnect the negative battery cable. Position it away from the battery.

Step 5: Decide where you want to install the gauge. First, you need to see how the gauge mounts: it may mount with attachment tape, or it may be mounted with screws.

If it has a screw mount, you need to make sure that it is mounted in a spot where screws will not hit anything inside the dash.

Step 6: Run the wiring between the gauge and the battery. Using the appropriate size wire, run wiring from where the gauge will be mounted to the positive battery terminal.

bright wire going through factory harness

  • Tip: When running the wire from inside of the vehicle and into the engine compartment it is easiest to run it through the same seal as the vehicle factory wiring.

eyelet connector crimped to wire

Step 7: Attach connectors to the wire you just ran and the fusible link. Strip ¼-inch of insulation from each end of the fusible link. Install an eyelet connector and crimp into place on one end, and crimp a butt connector on the other end.

Then connect it to the wire that you ran to the battery.

eyelet connected to terminal

Step 8: Remove the nut from the positive battery cable end clamp bolt. Install the eyelet and tighten the nut back into place.

Step 9: Install an eyelet to the other end of the wire. You will install this eyelet where the wire will mount to the gauge.

Step 10: Find the wire that goes to the lighting circuit. Use your wiring schematic to locate the positive wire that supplies voltage from the light switch to the lights.

Step 11: Run a wire from where you are mounting the gauge to the lighting circuit wire.

three wire crimp connector

Step 12: Remove ¼-inch of insulation from the circuit end of the gauge wire. Using a three wire connector, crimp that wire to the lighting wire.

Step 13: Attach an eyelet to the end of the wire you just ran from the lighting circuit wire. Remove ¼-inch of insulation from the gauge end of the wire and install an eyelet connector.

ground wire bolted to body

Step 14: Run a wire from the gauge to a grounding point under the dash.

Step 15: Attach an eyelet to the wire running to the grounding point. Remove ¼-inch of the insulation from the wire, install an eyelet, and crimp into place.

Step 16: Install the eyelet and wire to the ground connection.

Step 17: Attach an eyelet to the end of the wire that will connect to the gauge. Remove ¼-inch of insulation from the wire at the gauge and install an eyelet.

three wires placed in back of gauge

Step 18: Connect the three wires to the gauge.The wire going to the battery goes to the signal or positive terminal on the gauge; the wire connected to the ground goes to the ground or negative terminal. The final wire goes to the lighting terminal.

Step 19: Install the gauge in your vehicle. Make sure to mount the gauge according to the gauge manufacturer’s instructions.

wire loomed around group of wires

Step 20: Wrap the wire loom around any exposed wiring.

Step 21: Install the negative battery cable and tighten until it is snug.

Step 22: Remove the memory saver.

Step 23: Start your vehicle and verify that the gauge is working. Turn on the lights and make sure the gauge is illuminated.

A voltage gauge is a nice addition to any vehicle, and can be a valuable safety measure for drivers who have recurring electrical problems in their cars, or drivers who simply want to take the precaution of knowing there is a problem before the battery is drained. There are a variety of gauges available, in both analog and digital, and in various colors and styles to suit your vehicle. If you are not comfortable installing the gauge yourself, consider using YourMechanic - a certified mechanic can come to your home or office to install one and ensure everything is working correctly with your gauges..

Next Step

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Mitsubishi Eclipse V6-3.0L - Valve Cover Gasket - Sunnyvale, California
This is the 4th or 5th time I've brought my car and my wife's car to Whitney. It's hard to find an honest mechanic that really knows what he's doing. It's really convenient for me because Whitney just shows up at my office and works his skills on the car (he brings all his tools & is fully equipped!), thus I don't have to worry about coordinating with my wife or co-workers to drop me off at a repair shop, pick me up afterwards, hit traffic during rush hour and miss work. And of course, the price point is important: it's way cheaper than taking it to a shop. When my Eclipse hit the 60K+ mile mark, I needed service. Whitney inspected it and told me what needed to be changed, and also told me what wasn't necessary. Then he did all the work in at my office's parking lot. I highly recommend Whitney to all my friends and family.
Honda Civic - Water Pump - Santa Clara, California
Friendly, professional, efficient. economical and well-skilled at his work. After a brief post installation overheat glitch, the car has been running well during the last month. Only suggestion for improvement is it can be challenging to reach Whitney with follow-up questions by phone. I would contact for continued service by Whitney and I recommend him to other customers.


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Tony was great, came out and got a new battery installed very quickly. Also gave advice on other maintenance issues I could address later on my own, great help!
Nissan Sentra - Pre-purchase Car Inspection - Union City, Georgia
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Pontiac Grand Prix V6-3.1L - Car is not starting - Richmond, California
Lamont showed up on time and we talked about the car before he did anything. He found the issue in no time, but unfortunately it was an issue only the dealership could fix. Lamont however, continued to check the car for any other issues and he provided me with all the necessary info I needed to get the car fixed. Overall Lamont is a good dude, I will be calling him for any other car issues I have in the future.

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