B7100 Hour Meter Troubleshoot

[lspecht]

Are you measuring 12 volts at the hour meter with the wires connected to the meter or with the wires disconnected from the hour meter? If you measure 12 volts with the wires connected it should be working. If you don't have the full 12 volts at the meter, you have resistance somewhere in one of your meter wires. Connect a parking light or turn signal lamp across the meter leads and make sure it has enough voltage and current to light. Measure the voltage with the lamp connected to make sure you are getting full battery voltage. If you have issues with the lamp lighting or measuring full batter voltage at the meter use a jumper to replace the wiring to the meter individually but make sure you are connecting positive to positive and negative to negative. Simply jumper from the negative lead of the hour meter to the battery and see what happens. Same thing with the positive lead. After you have determined which lead is bad (has resistance) carefully follow the wire looking for stress or signs of trouble on the wire. High resistance usually occurs at defective connections. Hope this helps

 

[bmblank]

Actually, now that I think of it, I also had some meter reading problems in the same area. I traced it back to a light bulb. I disagree with ispecht. If the hour meter is plugged in you'll get all sorts of strange readings, because now you're multimeter is in parallel with the hour meter. Same problem I had with the oil pressure light bulb. I pulled the bulb out and all of a sudden my reading fluctuations went away.

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[Sideofabarn]

Wolfman nailed it on the head about the regulator being the only thing that was sensitive to polarity. It's fried and needs to be replaced (see pic).

So dumb question-what is my next step? Can I just turn the battery around like it should be and start it up? Was the starter going backwards and was the engine running backwards as well?

 

[lspecht]

A good quality properly working voltmeter will virtually have no effect when placed in parallel with anything (unless you are working on super sensitive electronic circuits). There are loading factors but you don't have to know about them to work on a vehicle electric system. On a tractor, this will cause no problems
(retired state police radio technician, worked on hundreds of voltage issues on vehicles.) and a few on my tractors.

 

[Sideofabarn]

I flipped the battery around and hooked up the terminals....no smoke or anything burning!

I started the engine.....normal

Looked at the hour meter.........and it was clicking away. Works perfectly.


Thanks to everyone for their help. I would have never pinned the issue on the battery being backwards. It just needs a new regulator since it was fried and the battery does not appear to be charging. The regulator is on order.

 

[bmblank]

It shouldn't surprise me, as many times as I've heard of something like that, but it's hard to imagine plugging a battery in backwards.

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[D2Cat]

As a point of information, if you totally discharge a battery----then hook the charger backwards you will charge your battery backwards. Positive will be negative, negative will be positive!

 

[Jeff Gordon]

Jim,

I checked all three fuses behind the dash and cleaned the connectors-all look good.

When you say it has a bad ground is there a way I can check it. This is a dumb question but does the ground come solely off the black wire connected to the dial or does it also ground off where the dial touches the dash.

I agree that I'm missing something. The dial works like a champ when I connect directly to a 12v battery.

Thanks for the help.

had same problem with my b7100 ,upgraded to a digital meter works just fine,I could not understand why mine would run hooked direct also ,I'm thinking Grimlins!