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Discussion Starter · #1 · (Edited)
First, thanks xcopterdoc for the bed actuator information. I know you'll see this and I thought starting a new thread for a temperature issue might help others if needed. when starting my '97 6x4 diesel gator the cooling fan comes on right away along with the dash indicator light, I have coolant:). I assume I just need a new temp switch but before spending $80 the electrical diagram shows a B1 radiator core temp switch that when closed should allow the cooling fan to run but there is also a B2 engine coolant temp switch that lights up the H4 engine coolant light. Are both failed or does the B2 coolant switch close the B1 core switch but is not shown in the schematic? Apparently I have not memorized the wiring diagram:(
 

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The fan and light are 2 seperate systems.
The radiator core temp switch, when closed will complete the ground for the radiator fan. The hot wire to the fan is always hot and fan may run even with key switch off until rad core temps falls enough for switch to open. SOME LATER SERIAL NUMBERS USE A FAN RELAY. > 039741
The engine coolant switch, located at the thermostat housing, its only job is to tun on the coolant indicator light.
HOWEVER.. the coolant light also lights up when the glow plugs are on.
So it seems you have 2 different problems.
First the indicator light.. Does it ever go out? Even after running for more than 30 seconds? If it stays on, disconnect the orange/white wire at the engine temp switch. If it goes out, theres your problem. If it stays on for more than 30 seconds, chances are the glow plug timer module has gone bad. To check it, use a meter or test light and see if the glow plugs are staying on. If they stay on you have a bad module.
The fan running all the time is most likely the core switch. To check it, disconnect both black wires and using a meter, check to see if the switch is open (no continuity) or closed ( near 0 ohms ) If its closed, replace. If its open, then the ground wire to fan is grounded when it isnt supposed to be. UNLESS your serial number falls above 039741, then you may have a bad fan relay.
 

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Discussion Starter · #3 ·
I know it sounds like I'm taking the easy way out asking for advice instead of doing the trouble shooting but I can only get up north to work on the gator for a few hours at a time and try to have a game plan to save me some time, so thanks for your help. First, NO the light indicating a temp issue never goes out but I have put in a new glow plug module already so it sounds like that temp switch is failed. I personally don't care if the radiator fan comes on ALL the time right now so that puts that replacement on a lower priority level. I'm concentrating on getting it up and running safely with the proper indicators to let me know if something is wrong such as overheating or low oil pressure. I'll replace the temp switch so it actually comes on IF needed and move on to my brakes, which you've already helped me with but I haven't got there. I never said I couldn't drive it unsafely:), thanks again.
 

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Discussion Starter · #4 · (Edited)
oops, still may have a glow plug issue

This is my third edit because I'm an idiot and didn't take time to read and understand your response. You've given me the direction to follow and now it's METER time. I'm not frustrated, this is actually fun to learn and conquer the gator challenges:)
 

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SERIAL number?

The fan and light are 2 seperate systems.
The radiator core temp switch, when closed will complete the ground for the radiator fan. The hot wire to the fan is always hot and fan may run even with key switch off until rad core temps falls enough for switch to open. SOME LATER SERIAL NUMBERS USE A FAN RELAY. > 039741
The engine coolant switch, located at the thermostat housing, its only job is to tun on the coolant indicator light.
HOWEVER.. the coolant light also lights up when the glow plugs are on.
So it seems you have 2 different problems.
First the indicator light.. Does it ever go out? Even after running for more than 30 seconds? If it stays on, disconnect the orange/white wire at the engine temp switch. If it goes out, theres your problem. If it stays on for more than 30 seconds, chances are the glow plug timer module has gone bad. To check it, use a meter or test light and see if the glow plugs are staying on. If they stay on you have a bad module.
The fan running all the time is most likely the core switch. To check it, disconnect both black wires and using a meter, check to see if the switch is open (no continuity) or closed ( near 0 ohms ) If its closed, replace. If its open, then the ground wire to fan is grounded when it isnt supposed to be. UNLESS your serial number falls above 039741, then you may have a bad fan relay.
xcopterdoc, nice write up. As you may know I am new to the site, I am having a similar problem and have checked the core switch(2 black wires) and they showing 500 and rising. The light is working normal and it is definitely overheating but I cannot find the problem. I don't understand your comment about the "serial" number. Is this the engine or VIN? Also, I have 3 relays on the side rail where the fuel filter shutoff is at, do you know which one it may be? Do you know where I can also get a complete copy of the electrical system and users manual?

I did check my engine serial number and the last 8 are D05184X and the VIN is D025818, the unit is listed as a 2000 model 6x4 diesel. Any help would be greatly appreciated. Thanks, and by the way this just started happening after I installed a winch.

Gatorboy65
 

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Discussion Starter · #7 · (Edited)
lots of information already here to help

gatorboy65, when reading this message you should be able to scroll up and find a post from xcopterdoc. Click or touch on his name depending if you're on a computer or tablet/iPad and a drop down should open. pick the line that says something like "more posts" If you go through his replys you'll find some help he gave me on the electrical system with schematic plus a lot more that you'll be glad to learn. It doesn't take that long to read all the short messages but it's well worth it. But I'm sure he'll get back to you soon, he may be planting his spring garden today:)
I've got a 98 diesel and looking down on the relays on the rail from the passenger side the middle one is the glow plug relay, the right one (on mine) is the start relay and I assume that leaves the left one as the pull in coil cut out relay. If your fan is coming on but still running hot you may have an air pocket or faulty thermostat. These are discussed in xcopterdocs postings too. You can download the tech manual for about $10 from the web, well worth it. Also get the users manual for about $50-$60 (hardcopy). not as good for the money but still has valuable info for the gator.
 

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Gatorvirgin, thanks! I will do that. The fan does not come on at all, I was able to swap the 2 relays and it did not resolve the problem. I checked my grounds and they were also good. The next thing I did was to ground the fan directly to verify that it indeed was working and then I ran the gator until the temp light came on, at that point I tried to "ground" the core temp sensor on the ground side and it did nothing. So, with this in mind I believe it is the "radiator core temp sensor" which has went bad. Any ideas as to where to buy the TECH Manual and the sensor? Thanks!
 

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Discussion Starter · #9 ·
First, I might be dislexic, the glow plug module is in the middle but the start relay is left and pull in/cut out relay right. They are the same relay and interchangable. Sounds like you've found the smoking gun with the core temp switch. the easiest place to get replacement parts and manuals is a local John Deere supplier but online is a little cheaper if you aren't in a hurry and the cost of shipping doesn't make the bottom line equal:)
By the way, I went up north today and changed the oil/filter, replaced my temp switch (which was actually broken wire connector:() thermostat and new coolant, utilizing the "broom" technique to eliminate the air. I'm running very good now, for a change. What's xcopterdoc gonna do now???
 

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You know I didn't have problems until I disconnected the hose to install wires... I wonder is maybe I have air in the system as well. I will try the broom handle today... maybe it will fix my problem. I have circumvented the problem by running a ground wire from the fan and when it is running I merely ground the fan and it runs. quick fix not permanent. :)
 

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All fixed thanks to xcopterdoc and his posts, needed to BURP the system and used the broom handle method. Fan is working again as normal! wahooo... lol
 

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Glad yur all fixed up. the radiator core temp switch wont work if there is air in the system. The coolant wont flow thru the system. The engine will overheat and the rad will be ice cold. I guess you found all that out. When I worked at a JD dealer near Ft Bragg NC, we did hundreds of M-gators a year. Same as the regular 6x4 diesels with a few changes. I ended up buying a tool that goes in the neck where the cap goes. It pulls a vac on the system, then you swap the valve and it injects the coolant into the system. Slick as heck and no air... ever. Made life easy!
 
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