My Kubota M5700 has an issue with the fuel gauge. When I short the two prongs on the cable at the sending unit, the gauge goes to full. I replaced the sending unit and it still does not respond. The sending unit on this tractor appears to be a little different. It has to prongs. The sending unit has the float plus a straight rod that has a small cylinder looking thing at the end. Nether one of the terminals appear to have continuity to ground. I’m just wondering if this sending unit tests differently that others? Any suggestions here?
Kubota M5700 fuel gauge issue
- Thread starter mooreaud1
- Start date
You didn't say what the issue is. Your tractor has a typical gauge and a low level alarm. I think it turns on the charge light when the fuel level is low. Below is the schematic. You can see there is the typical variable resistor and what appears to be a fixed resistor, but is really a thermistor.
* When you remove the connector and turn the key on, the fuel gage should show empty.
* When you ground the yellow wire at the connector and turn on the key, the fuel gauge should show full.
* The fuel and temperature gauges share a voltage regulator - is the temperature gauge working correctly?
* When you remove the connector and turn the key on, the fuel gage should show empty.
* When you ground the yellow wire at the connector and turn on the key, the fuel gauge should show full.
* The fuel and temperature gauges share a voltage regulator - is the temperature gauge working correctly?
Sorry, I wasn't clear here. The gauge is not responding. There are two wires (conductors) that plug into the top of the sensor. And there is also a ground wire that attaches to one of the bolts/studs on the sensor mount. The temperature gauge is working. If I short the conductors on the wire, the gauge goes to full so I can only assume everything is ok before the sensor.
Have you tried shorting just the yellow wire to ground? Is that ground wire securely grounded at the other end? Is that ground wire possibly broken? Try a separate ground wire.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
found the WSM, it goes to the 'low fuel light' which is also 'charge' indicator.
I presume it might be a thermistor... cooled by fuel so light is off.....no fuel ,it selfheats light comes on ?
Overall nothing to do WITH the fuel gauge though....
I presume it might be a thermistor... cooled by fuel so light is off.....no fuel ,it selfheats light comes on ?
Overall nothing to do WITH the fuel gauge though....
OK…so you are talking about a temperature gauge…yet you post that if you short two wires it indicates “full”….(whatever THAT means… Do you mean full HOT..??….. or full COLD..??)….
If you can’t standardize your comments…(or at least DEFINE them)….. it’s difficult to help you.
If you can’t standardize your comments…(or at least DEFINE them)….. it’s difficult to help you.
I think his temperature comment was in response to my question. I had asked if the temp gauge was working, since it shares the voltage regulator with the fuel gauge.
GreensvilleJay
Well-known member
Equipment
BX23-S,57 A-C D-14,58 A-C D-14, 57 A-C D-14,tiller,cults,Millcreek 25G spreader,
re: When I short the two prongs on the cable at the sending unit, the gauge goes to full.
According to the wiring diagram in the WSM..
That isn't the proper procedure . One of those prongs is the fuel sensor, the other is the 'out of fuel' sensor.
To bypass the sensor, you connect the Yellow wire in the harness to ground. This should make fuel gauge go to 'over full'.
To test the 'out of fuel' circuit, you connect the Yellow/green wire to ground. This should turn on a light, 'low fuel/charge'.
According to the wiring diagram in the WSM..
That isn't the proper procedure . One of those prongs is the fuel sensor, the other is the 'out of fuel' sensor.
To bypass the sensor, you connect the Yellow wire in the harness to ground. This should make fuel gauge go to 'over full'.
To test the 'out of fuel' circuit, you connect the Yellow/green wire to ground. This should turn on a light, 'low fuel/charge'.
I'm talking about the fuel gauge, not the temperature gauge. The temperature gauge works fine. I posted that when you short the two wires at the connector, the fuel gauge goes to full (it does not respond otherwise). And now I know that is not the way to test it. I'm guessing the only reason the gauge went to full is that is saw ground through the low fuel light circuit. I know now to test the fuel gauge side of that connector to ground. I'm sorry I confused everyone here. I'll get to that later this week.
Ok, I think you nailed it. The ground wire in the harness was grounded to the top of the sensor but it was not grounded. It was totally open. It showed no continuity to ground once I disconnected it from the sensor. I found a good ground, ran a wire to one of the studs on the sensor and the gauge now works. I’m still a little miffed though. If the sensor is screwed down by the studs on the tank, it should be grounded. Correct? Why does it need a ground wire to work?
I
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Dunno. Plastic tank? Tank isolated from frame? K could definitely do better on their grounding.