Voltage Gauge issue - Drops below 12 sporadically but returns

Hi there,

Long time reader, first time poster.

I have a 2005 AC tundra SR5 4x4. I’ve been noticing an issue with my voltage gauge and wanted to post about it to see if anyone else has experienced something similar.

Every once out of maybe 15 drives, I experience a low voltage reading on my voltage gauge. This is usually how the event goes: I start the truck with the gauge reading ~13-14 V. I drive for about 30min -1.5 hrs before I notice that the voltage is reading low - below 12V. Sometimes I find it approaching 10 V or even close to the bottom of the gauge at 9 V when I get honed in on the road. It has never indicated a dash/warning light. When I discover this low reading, I will pull off the road and turn off the truck. It doesn’t make me feel very good driving with a reading that low. I turn off the truck for a minute then start it back up. The truck starts back up no problem and the voltage gauge reads back to ~13-14 V. Quite confusing. I continue to drive with no issue and with the gauge reading normally around ~13 V

I have tried to initiate this drop by running all the auxiliaries (lights, fogs, AC, etc.) but it seems to only happen randomly. One time after a longer drive around 2.5 hrs with no such low voltage reading, I stopped and got gas, and went about my way for it to begin slowly dropping over a course of 45 min to around 11 V or lower. Turned the truck back off at my destination, turned it back on and drove around some more for it to show a normal voltage reading.

My battery is about 2 and half years old, could it be that? Perhaps an alternator? I am confused that I get no warning/dash light when it gets really low. Very confused that when it does get this low, only a restart of the truck fixes the low reading and it begins to read normal expected voltages. I’ve taken a multimeter to it and got expected values while the truck was on and off. Maybe I ought to check it when I notice it happening and see if the gauge matches the reading. I will leave my multimeter in the truck and reply to this post to see if that leads to anything. I don’t have any wires / electrical components other than the factory wiring hooked up to the battery.

Took it to a mechanic for them to tell me it was just fine. So am just wondering if there is anyone out there who has had a similar issue. I’m leaning towards it being a battery issue, although 2.5 years doesn’t seem that old for a car battery. I like to think I am mechanically inclined, but sometimes I tend not to be as smart as I think so any advice or insight would be appreciated.


Thanks in advance.

 

You're on the right track. If the VOM doesn't match what your truck's gauge shows, well, good luck trying to figure that one out. I have a feeling the truck's gauge is erroneous.