Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Is a voltmeter adjustable?

September 29, 2013, 10:04:09 am

Our '89 dash voltmeter indicates 12 volts while the system monitor shows 13.7 volts for the house battery and the engine battery (two separate readings). Which should I believe?

The dash voltmeter is just a needle and never goes beyond 12 volts.

Is the dash gage adjustable?? On the back of the gage itself? Instead, get a volt meter that tells exact voltage supplied and then adjust gage?

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Re: Is a voltmeter adjustable?

Reply #1 – September 29, 2013, 10:06:01 am

Have you used your digital voltmeter to check voltage at the back of the gauge?

 That will tell you if the gauge or small wires/many connections/other loads on the same wire are the source of the erroneous readings.

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Re: Is a voltmeter adjustable?

Reply #2 – September 29, 2013, 11:02:45 am

If there are other gauges in the dash also reading low(esp. engine temp and oil pressure) then check for poor grounding behind the dash.

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Re: Is a voltmeter adjustable?

Reply #3 – September 29, 2013, 04:16:02 pm

nighthawk,

I don't know about your '89, but on a 2002 with VDO dash voltmeter, there is an adjustment on the side of the meter. You have to unscrew the collar from the meter and remove it from the dash panel to see the hole in the threaded area.

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Re: Is a voltmeter adjustable?

Reply #4 – September 29, 2013, 11:11:53 pm

This is an Oshkosh volt meter with a needle pointer. It points to about 12.8 volts with the engine running. My handheld volt meter reads 13.2 volts, as well as the dash monitor.

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Re: Is a voltmeter adjustable?

Reply #5 – September 30, 2013, 07:47:49 am

If you remove the gauge from the dash, hopefully you will find the adjustment.

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Re: Is a voltmeter adjustable?

Reply #6 – October 02, 2013, 08:57:30 pm

I'd be very surprised if you have an adjustment on that older coach; or mine for that matter. I just make a mental adjustment, myself.

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Re: Is a voltmeter adjustable?

Reply #7 – October 02, 2013, 11:55:38 pm

I decided that, with my back condition and the gage location, it would be too painful to attempt to remove the gage. It would require me to lean over the steering wheel and almost stand on my head in order to see the back side of the gage. I now know what the discrepancy between actual and the dash gage is so I will just do a mental correction and let it go at that. But thanks everyone for the advice.

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Re: Is a voltmeter adjustable?

Reply #8 – October 03, 2013, 05:27:57 am

Interesting, my DC gauge is fairly close to correct, it is just a 32 Volt meter, WHY would they use a 32 Volt meter?

God Bless the VMSpc, another reason I do not pay attenton to the dash except for the air pressure gauges.

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