Troubleshooting Voltmeter

[300sflyer]

I have a 94 Mercruiser 5.7 with an Alpha 1 gen 2 outdrive. When the engine is not running, I have 12.6 volts at the battery and zero voltage showing on the volt meter in the dash, with the ignition key in the run position.

With the earmuffs on the drive, and the engine running, I have 14.5 volts at the battery, and still nothing showing on the gauge in the dash.

If I measure the voltage at the back of the gauge with the engine running, I also see 14.5 volts.

I assume this means my volt meter in the dash is the problem, and I need a new one?

Thanks,

 

[searay3]

Re: Troubleshooting Voltmeter

Check the ground. An ohm meter from the gauge to a known good ground. It may be clustered with ground wires from everything. I've seen where they bundle together and make for a bad connection. If that checks out, gauges do go bad..

 

[300sflyer]

Re: Troubleshooting Voltmeter

OK... Will do. I should add too that all the other gauges are normal.

 

[v1_0]

Re: Troubleshooting Voltmeter

I have a 94 Mercruiser 5.7 with an Alpha 1 gen 2 outdrive. When the engine is not running, I have 12.6 volts at the battery and zero voltage showing on the volt meter in the dash, with the ignition key in the run position.

With the earmuffs on the drive, and the engine running, I have 14.5 volts at the battery, and still nothing showing on the gauge in the dash.

If I measure the voltage at the back of the gauge with the engine running, I also see 14.5 volts.

I assume this means my volt meter in the dash is the problem, and I need a new one?

Thanks,

You could try to hook the voltmeter directly to a battery and see what it reads. If it works, then your wiring is suspect. If it dosn't then your voltmeter is.

 

[abj87]

Re: Troubleshooting Voltmeter

If I measure the voltage at the back of the gauge with the engine running, I also see 14.5 volts.

I assume this means my volt meter in the dash is the problem, and I need a new one?

Thanks,

Yes it does. Throw a new gauge in and your good to go.

 

[300sflyer]

Re: Troubleshooting Voltmeter

Ok ... so I have the gauge removed, and it is showing infinite resistance threw it, so I am 99.9 % convinced it's toast... I will order a new one.

Thanks guys!

 

[abj87]

Re: Troubleshooting Voltmeter

Ok ... so I have the gauge removed, and it is showing infinite resistance threw it, so I am 99.9 % convinced it's toast... I will order a new one.

Thanks guys!

yep its junk...

 

[bruceb58]

Re: Troubleshooting Voltmeter

A voltmeter should be a low impedance input so it supposed to read very high. Typically, you don't test a voltmeter by measuring the resistance across the inputs. In the case of a boat guage you may read lower than infinite with a good meter becuase of the needle movement but I wouldn't rely on that way of testing it.

If you measure the voltage at the two inputs of the meter and it measures a voltage at that point, your meter is bad.