What makes my voltage gauge read low when the engine is running?

Oluseun, with the engine running the gauge should measure the output of your alternator. The low voltage may be indicative of issues with your alternator. If you have one of those that shows the voltage without the engine running, then check your gauge for a bad resistor on the dash panel.

What should battery voltage be on GM Truck?

It appears the needle fluctuates between 12 and 15 or volts. The battery gauges on most vehicles I have owned stays around 13 to 14 volts and doesn’t move much unless something that consumes a lot of power is turned on. Mine does this with nothing additional running on the truck other than the radio and a/c.

Why does the battery gauge go back to 12 volts?

When your gauge read ~12volts and a new battery it went back to 15 volts, the old battery was overloading the alternator with an internal short. At one time I had a battery short bring it down to 9 volts and the computer went nuts. The engine back fired I just made it to a battery shop.

What’s the voltage regulator on my Silverado truck?

The truck now has 85,000 miles and on my way to go camping (about 125 mile trip one way) the voltage regulator dropped to around 11 or 12. Of course I panicked and found the nearest parts store to check for a bad alternator, they said all good no problems.

Why does the battery Guage drop to zero?

Once it drop it stays there until the truck is shut off and restarted. There’s a code P1682 battery charging voltage low. I’m assuming it’s either a bad connection on a problem in the PCM. Disconnected and re-connected the plugs on the PCM.

Why does the battery voltage go all the way down?

When it does it the voltage gauge on the dash goes all the way down. Then shutting the truck off and turning the key on (not starting the engine) the gauge reads a normal reading. Also the 14.0v at the battery makes it look like the alternator is charging. EDIT : It was the alternator (read further down for details).

Why does the dash gauge switch from battery to alternator?

OK now that is starting to make sense. If the dash gauge switches over from reading battery voltage to alternator voltage after the engine starts, and there’s a diode between the alt. output and the battery, it would explain a lot. I will take readings at the alternator and let you know what I find.

What’s the voltage on a Dodge Key Truck?

Turn the key truck starts right up, battery gauge will be right around the 10volts mark for about 5 seconds. Then voltage jumps right to 14+ for about 5 secs then back down to about 10 volts for 5 seconds and then back to 14 where it will eventually stay.

What should the ground voltage be on an injector?

One will be connected to ground and will read 0 volts. The other should read around 12 volts. Step 5: Repeat with all injector wiring harnesses. Leave the ground lead in position and test all of your injector wiring harnesses. They should all be around 12 volts. A lower reading means there is excess resistance in the wire somewhere.

What does a low voltmeter reading on a Dodge mean?

Another low reading would mean that your battery is bad or that you have a short circuit in the wiring. Disconnect the voltmeter from the battery posts and ask a friend or family member to get behind the wheel and start the Dodge. Then reconnect the voltmeter to the battery exactly as you did before.

How to test for 5 volts on MAP sensor?

You can test for these 5 Volts with the MAP sensor’s electrical connector connected to the MAP sensor or not, just avoid probing the front of the connector. Now Ground the black multimeter test lead on the battery’s negative post. Your multimeter should show you 4.5 to 5 Volts DC.

What does no light mean on a 6V ignition?

No light means you’re not getting power to the coil. Light pulsing on or off, or varying in intensity, means you have a high resistance connection somewhere in the power circuit.

Is the 6V ignition switch the same as the 12 volt?

It’s really essentially no different that a 12-volt conventional ignition system with the exception of no ballast resister, so apply exactly the same trouble-shooting technique. Are you sure the ignition switch is functioning (is there primary current at the coil?).

What are the symptoms of a bad voltage regulator?

One of the first symptoms of a failing or faulty voltage regulator are dim or flickering gauges. Since it’s the regulator that supplies power to the gauges, the gauges will start to dim and flicker if there’s an issue with the power supply.

Why is my mobility scooter not reading the battery gauge correctly?

But vast majority of the time, it is because they are not reading the battery gauge correctly. The first problem is that they read the battery gauge while the scooter is moving. This is wrong, because the battery needle or light drops when the scooter is using power.

What does it mean when your battery is reading 0 volts?

If your battery is: Reading 0 volts, chances are the battery experienced a short circuit Cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell Fully charged (according to the battery charger) but the voltage is 12.4 or less, the battery is sulfated

What should the alternator reading be when not running?

Using the panel voltmeter, the reading should be around 12 with the ignition on, not running, and no other loads. When cranking it may drop down to 8 or 9 volts. Once started, it should almost immediately jump up by 2 volts or better to around 14 volts (you might need to rev to 2000 RPMS or so).

When to troubleshoot an unusual voltage system drop?

Troubleshooting for Unusual Voltage System Drops Usually, the first sign that your charging system is in trouble is a “battery,” “ALT,” or “CHARGE” warning light illuminating on your instrument panel while driving. It means that for some reason, the alternator has stopped charging the battery and your car is running on battery power.

What does it mean when gauges in your car stop working?

But when the gauges in your car stop working, it’s not a situation you can safely ignore. When one gauge stops working, the problem may be in the gauge itself or a bad sensor, while all the gauges cutting out at the same time often indicates a blown fuse or a defective instrument cluster.

Why is the light on my tachometer not working?

LED displays that have been in use for long, may blank out due to damage. Getting the LED display replaced will fix the problem quite easily. This is the simplest task when troubleshooting a tachometer. Sometimes, corroded wire connections and breakage may be the reason for the tachometer not working.

What to do if your gas gauge fails to move?

If the float is OK and the float arm seems to be swinging freely through its full range, replace the tank unit. Ground the gas tank terminal post of the tank sending unit using a jumper wire. If the dash gauge now reeds empty, the gas tank unit is defective. If the dash gauge needle fails t move, the dash gauge is defective.

What causes the idle voltage on a GMC Yukon?

Items that affect the vehicle’s electrical system current and voltage at idle are the number of electrical loads being used, including add-on accessories, and extended idle times.

Why are the lights dimming on my GMC Yukon?

Dimming of the lights is an indication that current is being pulled from the battery. If the battery is in a low state-of-charge (discharged condition), the driver will notice a more pronounced dimming than a vehicle with a fully charged battery. 2.

When does the voltage drop in a truck?

You should be testing this at around 1500 to 2000 rpms as that is normal operating range. In my truck when I engage the turn signal I can watch my voltage gushed drop with each click when I am at idle. When driving at highway speeds, this not nearly as noticeable.

What’s the battery voltage on my GM 05?

My 05 does the same thing with a new alternator and battery. In the city it is around 14 volts, when I get on the highway it drops to 11-12 volts. If I put all 4 windows up at the same time the lights dim for a second and then the voltage goes up to 14-15 volts.

What makes my car voltage gauge read low?

As a vehicle slows, engine/generator RPM slows and the current (amperage) output of the generator may not be sufficient to supply the loads, the vehicle system voltage will drop and the lights will dim. Dimming of the lights is an indication that current is being pulled from the battery.

Items that affect the vehicle’s electrical system current and voltage at idle are the number of electrical loads being used, including add-on accessories, and extended idle times.

What causes an alternator to output low volts?

If the voltage at the battery and alternator don’t match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring. While applying the same conditions as above.

What does it mean when battery and alternator don’t match?

Also the voltage at the battery and the voltage at the alternator should be within 0.5v of each other. If the voltage at the battery and alternator don’t match. For example the battery reads 12v and alternator reads 14v. This means that there is an issue with wiring. While applying the same conditions as above.

How can I tell if my alternator is bad?

If the voltage is higher than that examine all the negative cabling for problems. Preform the same test with the positive side. Place the red lead on the positive battery terminal (if possible dig it into the battery post, not the terminal). Place the black lead on the bad post of the alternator.

What should the alternator voltage be with the engine running?

With the engine running it should be reading alternator voltage, should be around 14.4 DCV, that could vary depending on the needs of the electrical system at that time. If it is reading below 12.6 DCV with the engine running you are probably running off the battery. It will only run untill the battery dies, if the alternator is not charging.

Is it normal for an alternator to not charge?

Still, it’s perfectly normal for others to see the alternator not charge at all intermittently. One test is not enough if you are diagnosing a charging system problem. All too often, the alternator is condemned as the source of the problem if only battery voltage is present with the engine running.

When to use battery light to test alternator?

The other critical tool to effectively diagnose an alternator is a scan tool. On older vehicles, the battery light would turn on the alternator light when the alternator output or battery voltage dropped below a preset value. The battery light on modern vehicles, however, is controlled by data and trouble codes.

What makes my voltage gauge read low when the engine is running?