John Deere 250 Temperature Gauge and Preheat Issues

[N4HMRHAM]

I have a 2003 JD 250 Series II skidsteer that has been parked for about 3 or so years. 1.000 hour service was done back then and it has about 1,033 hours on it now. Chg'd the battery and it started almost immediately.

I have two issues:
1. The engine coolant temperature gauge is not reading mid-scale as it should. When the engine is warmed up, I can feel hot water alternating through the upper radiator hose, so the thermostat is working. It gets hot enough that I can't keep my hand on it for very long. I haven't used a thermometer to check the temperature but will do so soon.

The temp gauge only rises to about 1/5 or so of the way over, maybe 2 needle widths above where the solid green bar starts. Stays steady at that point even while the thermostat cycles. It used to be a solid mid-range. I have the repair manual on this machine and have reviewed it thoroughly.

My next step in this diagnosis is to disconnect the two wires going to the engine coolant sensor (mounted on the top rear of the engine). The sensor is a two function unit - one parts deals with the normal engine temperature and feeds the gauge. The other part is the engine over temperature switch that feeds an led. The test is to apply a hard ground to the gauge wire and it should read full hot if all is well upstream.

What I need right now is for somebody to advise me on how to remove those two Dang connectors. I have pulled on each with a reasonable amount of force but they don't come off. When looking straight down on the top of each connector, I see a protrusion of the plastic housing on the inside of one side of the housing.

Logic says that there is a tab or something similar down below the metal clip that is contained in the housing, and this tab is interlocking with a slot or something with the spade rising up from the sensor section.

So what is the trick to get them off? A thin flat blade or VERY small pocket flat screwdriver? WHAT?

2. The manual Preheat function isn't working. When I press the switch there is no voltage drop on the battery. It used to drop a full volt or more when activated. I haven't spent any time on this problem yet but same issue as above.

I need to know how the disconnect the wire from the top of the heater unit AND how to get the wires off the Preheat relay (located near the heater). My first test on this will be to apply B+ to the pick coil connector - relay should pick and feed battery to the heater unit. If it does then the problem is back toward the switch.

So, can someone (or someones) educate me on these points, please? There ain't one @#$% word in the 300+ page manual on how to do that. It sez "Disconnect the wires from ...". Fine! How the H... do you do that?

I called JD Construction and Forestry Tech Support and the bozo that answered didn't know how to do it either. Said to call a distributor. Thank him very little. Called a local distributor but haven't heard back yet.

Any help very much appreciated.

Fred

 

[flyerdan]

I moved this to the JD forum where it's more likely to be seen by those who are familiar with it.
I also went ahead and put in paragraphs where you intended them.

 

[N4HMRHAM]

I moved this to the JD forum where it's more likely to be seen by those who are familiar with it.
I also went ahead and put in paragraphs where you intended them.

Flyerdan - Is there some guide available to edit a post structure? I've never had to do this elsewhere! ????

 

[N4HMRHAM]

Flyerdan - Is there some guide available to edit a post structure? I've never had to do this elsewhere! ????

Meant to thank you for busting it up. Certainly should be more comprehensible.

 

[flyerdan]

Meant to thank you for busting it up. Certainly should be more comprehensible.

The guide that I use is HTML Cheatsheet , and I cut and paste the code snippets as it's easier and more accurate.
For simple paragraphs I put a pic example in the other thread.

 

[mg2361]

The thin flat bladed screwdriver is the ticket. There is a little tab down in there that engages the spade of the sender but it should come off with a little help from the screwdriver. The line at the beginning of the green should be 158 deg F. The line in the middle of the green is supposed to be 194 deg F. The large spade terminal on the sender to the engine block should be 2.21K - 2.69K ohms @ (20°C) 68°F, 1.65K - 5.88K ohms @ (0° to 30°C) 32°F to 86°F. Did this unit ever have the ground improvement performed on it. Those machines had a lot of ground issues. Make sure all ground connections everywhere are in perfect condition and shiny clean.

 

[farmshop]

The thin flat bladed screwdriver is the ticket. There is a little tab down in there that engages the spade of the sender but it should come off with a little help from the screwdriver. The line at the beginning of the green should be 158 deg F. The line in the middle of the green is supposed to be 194 deg F. The large spade terminal on the sender to the engine block should be 2.21K - 2.69K ohms @ (20°C) 68°F, 1.65K - 5.88K ohms @ (0° to 30°C) 32°F to 86°F. Did this unit ever have the ground improvement performed on it. Those machines had a lot of ground issues. Make sure all ground connections everywhere are in perfect condition and shiny clean.

They were also bad at taking out displays. I assume you checked the fuses regarding the pre heat?