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.