Volt meter reading voltage when disconnected

[rwmastel 47]

I've got my dash apart, and noticed that with no wiring connected, the voltage meter reads 13 volts!  Normal?  It also reads that when installed, with key off. I thought it was just always reading the battery. 

I'll have to go out and tilt it different directions to make sure it's not just gravity acting on the needle. 

Edited June 3 by rwmastel

[WHX?? 48,853]

Most likely a stuck needle. Try tapping on it lightly or wave a magnet in front of it. 

[ebinmaine 67,766]

I've had em read whatever they were at when the engine electrical was last shut off. 

 

6 minutes ago, WHX?? said:

Most likely a stuck needle. Try tapping on it lightly or wave a magnet in front of it. 

 

Tried the tapping. Never thought of using magnet...

[rwmastel 47]

Moving the panel around doesn't make a difference.

 

When installed, it reads like this with key off, and then it goes to max as soon as the key is turned to first position (before starter cranks).  Stays there during operation, and goes back to 13v when turning key off.

Edited June 3 by rwmastel

[ebinmaine 67,766]

8 minutes ago, rwmastel said:

Moving the panel around doesn't make a difference.

 

When installed, it reads like this with key off, and then it goes to max as soon as the key is turned to first position (before starter cranks).  Stays there during operation, and goes back to 13v when turning key off.

 

Do you have a hand held voltmeter meter?

 

Sounds like your gauge is outta whack.  

[rwmastel 47]

I do have a multimeter (2 actually!).  Can I check resistance across pins on the gage for continuity?  Maybe the connectors were reversed by some previous owner?  Would like to confirm if a new gage is needed.  Thanks!

[rwmastel 47]

I guess I could put little alligator jumper leads from the battery (on the workbench) to the meter and see if it works appropriately.  If so, maybe the wires in the mower are damaged. I'll post the test results. 

Edited June 3 by rwmastel

[ebinmaine 67,766]

4 minutes ago, rwmastel said:

I do have a multimeter (2 actually!).  Can I check resistance across pins on the gage for continuity?  Maybe the connectors were reversed by some previous owner?  Would like to confirm if a new gage is needed.  Thanks!

 

I'm not sure on how to diagnose the gauge itself ..

I've only ever dealt with the older style and reversing them was impossible without getting a reading that was way way off. 

[Rick3478 428]

If it moves, continuity is not the problem.  These are suppressed-zero indicators, should go to left peg when off.  If it has a rubber plug in the back it may be adjustable, but more likely not.  And it's probably swaged together, not really intended to be repaired.

[squonk 41,171]

Meter is junk. They aren't the best quality to begin with. 

[Handy Don 12,281]

6 hours ago, rwmastel said:

Moving the panel around doesn't make a difference.

 

When installed, it reads like this with key off, and then it goes to max as soon as the key is turned to first position (before starter cranks).  Stays there during operation, and goes back to 13v when turning key off.

IMHO, busted and irreparable....but to confirm, i’d use some jumper wire to set up direct battery connection with everything else off. Reversing polarity should not break the meter.

 

I’ve replaced one with an analog from the jungle site with success on the 500 tractor but for the 854 I got a marine digital waterproof gauge for < $20 and it's easier to read! 

 

[rwmastel 47]

52 minutes ago, Handy Don said:

IMHO, busted and irreparable....but to confirm, i’d use some jumper wire to set up direct battery connection with everything else off. Reversing polarity should not break the meter.

 

I made jumper wires with alligator ends (a first for me!) and connected battery to gage on bench.  Same behavior.

No power = 13v

Power = Max v

 

There is a red plastic plug on the back, but I didn't notice anything behind it.  There's also a third connector with a plastic cover on it, marked S.

[Handy Don 12,281]

1 hour ago, rwmastel said:

There is a red plastic plug on the back, but I didn't notice anything behind it.  There's also a third connector with a plastic cover on it, marked S.

On some tractors, the gauges had a port on the back into which one could insert a lamp to illuminate the gauge. Would have been about ⅝-¾” in diameter.

 

I have no idea what the “S” port might be but maybe for calibration? If yes, it’d likely take a small, jeweler-size screwdriiver. Try using the magnifier app on your phone to peek inside!

 

If it IS for calibration:

The more likely scenario is that you would adjust a small, variable resistor inside the gauge. That might look like one of these two:

First, turn it gently back and forth just a few degrees to be sure the contacts are clean. Then, hook the meter to a battery whose voltage you know for sure via a decent VOM. Lastly, adjust the resistor so the gauge shows the voltage of the battery.

 

The less likely scenario is that the screw would manually adjust the mechanism so it aligns with the voltage. In your case, you’d gently turn the adjuster a few degrees in both directions while watching the needle with no battery connected. If it moves, then gently adjust the needle to zero.

Edited June 4 by Handy Don

[rwmastel 47]

I was happy with the spring's action, so I put everything back together tonight.  I used electronics cleaner on all the connectors - every device (key switch, volt meter, hours meter, pto lever safety switch, 3 warning lights).  Nothing happens when turning the key.  If I start taking the dash apart again, I'll look for an adjustment in the gage.  Until then, I'm leaving it alone and focusing on the electrical start issue - new thread to start.

Edited June 4 by rwmastel