Fuel gauge and temperature gauges pegging to full fuel and hot after 45 - 60 minutes.

[REWDOC]

I have had a 1996 L2900DT for 10 years with 1150 hours. About 9 months ago, I noticed temperature gauge pegged in the red hot zone. I replaced the thermostat and thought I had fixed it. I did not use it much over the winter, but this Spring the temperature gauge pegged in the red again. I took it to a local mechanic who thought it was from a blown head gasket or cracked head. He inspected the head and replace the gaskets. It continue to peg the red zone after 1 to 1.5 hours. He then replaced the radiator and temp sensor without benefit. I decided it was too expense to let him continue replacing parts. I bought a thermal gun and discovered that the tractor was not hot. The block read 175 - 185 when the gauge was in the red zone. The radiator read 154. I have check this multiple times and the tractor is not overheating. 2 days ago the fuel gauge started pegging the full mark after 35-40 minuets followed by the temperature gauge going in to the red zone after 40-60 minuets. From what I read, both gauges will peg full or hot if the wires go to grounded. Has anyone had this problem and know how to fix it. I'm wondering if I have to replace the wiring harness, but this would be expensive. I've thought about replacing the electric temperature gauge with a manual gauge but that does not solve the problem with the fuel gauge.
Thanks

 

[Bee-Positive]

W.A.G.

Couldn't find an electrical diagram for your L2900 so I looked at the previous model L3010. Maybe someone on OTT can hook you up with a WSM.

On the L3010 the temp and fuel gage share a voltage regulator - #1 on the diagram. If your L2900 has the same set up then bad voltage from the regulator could make the gages read incorrectly. Try replacing the that. Sorry I don't have a model number for that part.

Also sorry you potentially dropped a lot of $$$ on unnecessary repairs.

 

[REWDOC]

Thank you.

 

[GeoHorn]

Mechanical gauges “usually” operate similarly…. a bi-metallic strip is wrapped in resistance-wire that heats up and causes the strip to bend and move the indicator needle. The sending units simply regulate the “quality” of electrical-ground the gauge sees.
This means that an electrical “short” in the wire between the gauge and the sensor will cause the gauge to read full Hot… or full fuel.… (as will a shorted/failed sensor but that’s unlikely in this case….but check to see anyway.)

Mice love to chew on wire-insulation and often cause this failure.

A broken wire between the gauge and sensor will have the opposite indicaiton…. a COLD or EMPTY indication.

Hope this helps.

 

[whitetiger]

Here is the wiring schematic for your tractor.

 

[Hugo Habicht]

From your description it could be a faulty ground connection to the instrument panel too.

 

[RCW]

I have to clean the spade connector on the temperature sending unit occasionally. Add a little dielectric grease.

 

[REWDOC]

Thanks everyone. I let you know when I get it solved.

 

[Russell King]

You may be able to just run new wires from the sensors to the gauge instead of making a new harness. I don’t have a clue how either end of the wires are terminated and that might be the most difficult part of the problem.

 

[Bee-Positive]

Water proof connectors. McMaster-Carr has Submersible Insulation-Piercing Butt Splices.
As long as the connections to the gage and sensor are good just cut them long, run a new wire and splice each end.

 

[RCW]

I have to clean the spade connector on the temperature sending unit occasionally. Add a little dielectric grease.

Happened again today and made me think of this thread

Started tractor and temp gauge was already up halfway.....something's up.

Within 5 minutes, it's reading pretty toasty. (It was 90 degrees at the time)

With laser thermometer, check radiator top neck (139 degrees), top rad hose (135), and block on fan side of exhaust manifold at 171 (156 when I took pic).

Not even up to temp yet...... I always assume the gauge is correct until proven otherwise.

Clean and put some dielectric grease on spade connector. Back to mowing in 5 minutes.....

Looks like your tractor has same/similar temp sensor.

May not be your issue, but for a couple minute's time, worth a try.......

 

[REWDOC]

W.A.G.

Couldn't find an electrical diagram for your L2900 so I looked at the previous model L3010. Maybe someone on OTT can hook you up with a WSM.

On the L3010 the temp and fuel gage share a voltage regulator - #1 on the diagram. If your L2900 has the same set up then bad voltage from the regulator could make the gages read incorrectly. Try replacing the that. Sorry I don't have a model number for that part.

Also sorry you potentially dropped a lot of $$$ on unnecessary repairs.
View attachment 159501

Thanks for sending this. I think this is the problem with my L2900. However, the Kubota parts department does not have a replacement part for the voltage regulator listed as #1 on the diagram. I'm wondering if it is part of the circuit board. The only voltage regulator that they have a part number for is in the alternator. I cannot find a part number for the circuit board and a replacement for the whole dash assembly is no longer avalable. I'm not sure what to do from here.

 

[Bee-Positive]

Like my post stated it was only a WAG (Wild A$$ Guess) based on an earlier model tractor.

As shown in the correct wiring diagram posted by whitetiger I don't see any regulator between the sensors and the gages. Looking at the parts list from kubotabooks.com I don't see one either so the Kubota Parts Dept. would naturally say what they said. I know that doesn't help you, but here we are.

Have you actually taken the gage panel off and checked for corrosion, moister, dirt, loose connections, etc.?

P.S. - I looked up replacement gages on Messick's and almost choked at the prices.

 

[REWDOC]

W.A.G.

Couldn't find an electrical diagram for your L2900 so I looked at the previous model L3010. Maybe someone on OTT can hook you up with a WSM.

On the L3010 the temp and fuel gage share a voltage regulator - #1 on the diagram. If your L2900 has the same set up then bad voltage from the regulator could make the gages read incorrectly. Try replacing the that. Sorry I don't have a model number for that part.

Also sorry you potentially dropped a lot of $$$ on unnecessary repairs.
View attachment 159501

W.A.G.

Couldn't find an electrical diagram for your L2900 so I looked at the previous model L3010. Maybe someone on OTT can hook you up with a WSM.

On the L3010 the temp and fuel gage share a voltage regulator - #1 on the diagram. If your L2900 has the same set up then bad voltage from the regulator could make the gages read incorrectly. Try replacing the that. Sorry I don't have a model number for that part.

Also sorry you potentially dropped a lot of $$$ on unnecessary repairs.
View attachment 159501

Like my post stated it was only a WAG (Wild A$$ Guess) based on an earlier model tractor.

As shown in the correct wiring diagram posted by whitetiger I don't see any regulator between the sensors and the gages. Looking at the parts list from kubotabooks.com I don't see one either so the Kubota Parts Dept. would naturally say what they said. I know that doesn't help you, but here we are.

Have you actually taken the gage panel off and checked for corrosion, moister, dirt, loose connections, etc.?

P.S. - I looked up replacement gages on Messick's and almost choked at the prices.

Both guages peg. The fuel guage after about 45 min and the temp guage after about 1 hour 15-30 miin. I had it appart last month and everything looked OK. I will try to take the instrument panel appart again this weekend and check the ciruit board closely for cracks in the circuits. Also, we will try running it with the alternator disconnected to see if it still does the same thing, $1,200.00 for a new panel and $550.00 for a used one which looks much worse than mine.
Thanks again

 

[Bee-Positive]

And a new panel may not even solve your problem. Wiring up your own sensors and mounting them to the top of the panel would be less expensive.

I've got to believe it's a wiring/grounding/sensor issue of some sort.
Hang in there and keep at it.

 

[Workerbee]

Next time your gauges peg, get off and unhook the wires from the temp sender and the fuel sender. Dont let them touch ground. What do your gauges say? Then take an ohmeter from ground to the point on the sensors that the wires hook on. What does your ohmeter read?

 

[lynnmor]

There may be a voltage regulator built into the circuit board, I suggest that you Google "circuit board voltage regulator" so you can see the various components available. You might be able to replace some parts for very little money. Nobody today wants to repair boards opting to replace the whole thing.

 

[GreensvilleJay]

'both get pegged' is a sure sign that both temp and fuel sensor wires are 'shorted to ground'. As it 'comes and goes'...that'd most likely be a wiring harness/connector problem. Follow the wires, find out where the harness is being pinched,crushing the wires.

A 'bad' voltage regulator won't cause the problem.

 

[Hugo Habicht]

Not sure what "both get pegged" is supposed to mean, a more precise description of what is happening would certainly help for remote diagnosis.

A simulataneous short of two wires to ground is highly unlikely, so a common component to both meters is most likely the cause of the fault.

 

[GreensvilleJay]

fuel read over full, temp read super hot, ie both needles go far above the 'maximum; reading.
both circuits are typical 'old school' +12 from batt to voltage regulator to high side of meters, the sensor are connected to low side of meters and ground.
if you 'short a sensor', that meter will 'peg', go far above maximum.
for BOTH meters to do this then both must have their sensors shorted at the same time.