Irratic Indicated temperature on 2013 New Holland Workmaster 40

wursthorn · Aug 5, 2020

I have a 2013 NH workmaster 40. Starting about 2 months ago I noticed a high indicated temperature and climbing. I shut the tractor off and could find no overheating. When I turned the switch off it did not go to C as it should. But after turning the switch off and on twice it did return to C with the switch off and back just below half with the switch on. Everything seemed fine. It happens almost all the time now and the gauge has almost gone 360 a couple of times. However, after some setting and several switch off and on the gauge has gone back to C when turned off and when cold. The lowest resistance I have ever measured on the sensor (P/N MT40007156) so far when it goes to H and above is 47 Ohms. This would correspond to a temperature of about 180 degrees. At first I thought the sensor wire (yellow with a green tracer) may be shorting. So I went over all the wiring to make sure it was isolated from any engine or frame parts. I can find no place under the hood or dash that can touch any ground. I also added more wire sleeves etc to insure it couldn't. I have also unplugged and replugged all connectors. They look very clean. I have ordered a new sensor and will install it because it's relatively cheap. I have also ordered a new instrument panel (P/N MT 40244694). The only other components that may be a problem are the controller (P/N MT 40277142) and a twin relay (P/N MT40198043). Both of these items have a yellow wire with a green tracer going to them.
I will keep probing to see if the grounds are indeed grounded. I understand a Printed Circuit ground wire is blue and other ground wires are black. (I am not absolutely sure of this though) Other than this temperature indication problem the tractor runs fine. By the way I understand this tractor is the same as an LS3038)

If there is anyone out there with a good service manual or experience I would really appreciate whatever information, thoughts,etc. you can provide.

Thanks

Rebeldad1 · Aug 5, 2020

Be sure you are full of coolant. A sensor can be hot but engine/radiator cold with a stuck thermostat or head gasket issue.
They only show hot a time or two before major repairs are needed.

wursthorn · Aug 6, 2020

Rebeldad; thank you for reading my post. Yes, I had an employee who told me on her way to work the temperature wouldn't come up in her car and no heat from the heater until she stopped at a red light. She notice whenever she braked the temperature would go up. I suggested the car was actually hot but coolant was so low it wasn't touching the sensor until she put on her brakes. Sure enough she had just had her coolant changed and the mechanic hadn't filled it properly.. We added coolant to the proper level and that resolved her problem.

The only indication of something being hot is the gauge reading when the malfunction happens. All my tests and measurements indicate the coolant is not low and the temperature sensor which is in the thermostat housing are behaving normally. No actual overheating is occurring. My first thought after these tests was a shorting of the wire from the sensor to the electronics. I haven't found it. I am also looking for bad grounds. It could also be the gauge itself in the sealed instrument cluster. I have a new instrument panel coming ($165) which is little over an hour and a half shop time at the dealer.

At this point I really need a good service manual. Unfortunately those are hundreds of dollars. Also, the intermittent nature of the problem means I have to catch it when the failure is happening. I've noticed it never fails (reads hot) immediately from a cold start. It has to get to operating temperature (as verified by the gauge and resistance of the sensor unit) then when it fails the gauge keeps climbing without the resistance of the sensor unit changing. In fact it will climb almost all the way around to C. But nothing is actually overheating.

So, my plan at this point is when the instrument cluster arrives I'll install it. If that doesn't resolve the problem I'll disconnect the temperature sensor and install an aftermarket sensor and gauge totally separate from anything else in the tractor. When disconnected the gauge reads C for cold. At this point the only malfunction is the reading of the temperature gauge. Everything else appears to be working properly. I don't believe this tier 3 tractor uses temperature reading to control the injector. However, it could turn off the injector pump if the hot reading were real and not just the gauge reading. Thanks again.

wursthorn · Aug 8, 2020

Replacing the instrument panel seems to have resolved the problem.. Very noticeable difference in behavior. No longer erratic, stays a little under half and has never gone to hot. If this wasn't a solution I post again. I'm saving the old instrument panel for the lens.

DeepSea Smitty · Aug 26, 2022

wursthorn said:
Replacing the instrument panel seems to have resolved the problem.. Very noticeable difference in behavior. No longer erratic, stays a little under half and has never gone to hot. If this wasn't a solution I post again. I'm saving the old instrument panel for the lens.

I have the same tractor, it started spitting coolant this summer, 105 F in the shade here in Arkansas. Just turned 500 hrs. The gauge is operating correctly, I'm thinking the reservoir spitting is just from the heat... DM me and I can send you the tractor manuals...deepseasmitty@gmail.com