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post #1 of 15 Old 01-07-2019, 08:24 AM Thread Starter
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Gator TH 6x4 Glow Plugs not working

We have a 2 year old Gator TH 6x4 that gets daily use. The Glow plugs are not working. The light does come on the dash. I am wondering if there is a relay that could be the problem and the best what to trouble shoot. I did check the fuses and all fuses are ok. ANy advice would be appreciated. Thank you.
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post #2 of 15 Old 01-07-2019, 12:41 PM
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There is a glow plug module. I think it is on the inside of the right frame under the bed. There should be 2 identical relays with this module between them. Its about the same size I think but looks a little different. Not sure if you can test it?
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post #3 of 15 Old 01-07-2019, 03:58 PM
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Curious, how do you know they are not working?

Did you measure the resistance of each glow plug after it's been isolated from the others?

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post #4 of 15 Old 01-08-2019, 09:08 AM Thread Starter
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Quote:
Originally Posted by 200mph View Post
Curious, how do you know they are not working?

Did you measure the resistance of each glow plug after it's been isolated from the others?

The dealer checked the glow plugs and said they checked out. I did not check them. I know they are not working as the gator will not start when it is cold. So we put it in the barn and blow a heater on it and then it will start.

The light goes on - on the dash. I am wondering if the module is bad if the light on the dash still goes on ? Or maybe the dealer only checked one glow plug?
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post #5 of 15 Old 01-08-2019, 10:34 AM
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Hard cold starting just suggests they are not working. The GP themselves can be in working order, but not getting the supplied voltage.

I'd recommend removing the wire that feeds the GP's and measure voltage when the GP dash light is present. If no voltage this wire can be traced back to find the offending connection, fuse, relay, module, etc... (I'm fairly certain the voltage at the GP can not be measured unless they are removed from the circuit.)

Don't "Look" at a connection and say its good. Verify by voltage drop test or disassemble, sand/wire brush to ensure metal to metal contact. Many forum members have found issues with fuses not making good contact or corrosion within the fuse holder. It's always worth trying to disassemble/reassemble wire connectors a few times if difficult to clean otherwise.

Do you have a wiring diagram and description of how the GP circuit functions (found in workshop manual)? I have one for the 855D and it is very helpful, but likely not the same as your HPX.

Good luck and report back what you find.

2012 JD855D OPS Black Poly Roof, Deluxe Cargo Box, Front and Rear Protection, Power Lift, Front Hood Rack, Rear Screen (homemade), 800 Watt Inverter, 2500lb Winch installed in cargo bed, Front and Rear LED auxiliary lighting (4" square 27 watt), Front and Rear CV Guards, Koplin Side Mirrors
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post #6 of 15 Old 01-08-2019, 09:25 PM
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mine was hard starting for a couple years.. it would struggle and then it would finally come to life.. I'd put a meter on the glow plugs right at the plugs and they would get power until the timer had timed out.. glow plugs are cheap and I put in 3 new ones and it starts like a charm.. don't know why I procrastinated for so long..

Bernie
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post #7 of 15 Old 01-09-2019, 02:58 AM Thread Starter
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Thank you, everyone. So it turns out that two of the three glow plugs were bad. Since one was still working the dash light was still coming on (I guess). So I replaced all three. Apparently, the dealer must have checked the one that was working. The machine has 1900 hours on it So now I am left to wonder how long glow plugs normally last.
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post #8 of 15 Old 01-09-2019, 06:34 AM
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Congrats on finding the root cause and thanks for reporting back to help put closure to the thread.

I've never seen a definitive answer or a rule of thumb as to how long they last. Perhaps someone will enlighten the forum.

Did you buy the GP from JD or look up the equivalent part from NGK or other?

2012 JD855D OPS Black Poly Roof, Deluxe Cargo Box, Front and Rear Protection, Power Lift, Front Hood Rack, Rear Screen (homemade), 800 Watt Inverter, 2500lb Winch installed in cargo bed, Front and Rear LED auxiliary lighting (4" square 27 watt), Front and Rear CV Guards, Koplin Side Mirrors
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post #9 of 15 Old 01-09-2019, 09:22 PM
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my 6X4 has about 2300 hrs on it.. when I was putting up with the hard starting it probably had around 1700 hrs..(I've owned it since new so I knew they'd never been replaced) as I said earlier, I lived with it for an entire winter.. next time it gets even remotely hard to start there will be no waiting around.. new glow plugs right away..

Bernie
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post #10 of 15 Old 01-10-2019, 01:41 PM Thread Starter
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I bought it new and as I was away I had the dealer replace the glow plugs with what I assume were JD parts. If the problem arises again I intend to redo them myself with aftermarket glow plugs. I do not think the original glow plugs lasted anywhere near long enough.
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post #11 of 15 Old 01-10-2019, 10:13 PM
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Never crank when the glow plug light is lit. Never ever.
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post #12 of 15 Old 01-13-2019, 06:45 PM
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Quote:
Originally Posted by Jrhill View Post
Never crank when the glow plug light is lit. Never ever.
Why do you say this?

Modern glow plugs that I've seen have a full sheath protecting them from the combustion process and the heating wire is fully encapsulated to support it.

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Last edited by 200mph; 01-13-2019 at 06:47 PM.
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post #13 of 15 Old 01-14-2019, 10:24 AM
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Quote:
Originally Posted by 200mph View Post
Quote:
Originally Posted by Jrhill View Post
Never crank when the glow plug light is lit. Never ever.
Why do you say this?

Modern glow plugs that I've seen have a full sheath protecting them from the combustion process and the heating wire is fully encapsulated to support it.
The plugs are powered through a relay cause they pull a lot of amps and are timed, yes? When you turn the key to begin cranking while the glow plugs are heating you are pulling system voltage lower. That's not good, esp with a cold weather start. And just maybe the glow plugs will time out while cranking and when that does there will be more amps going through the relay. Yeah, it'll take it but at the expense of longevity. And its not best practice for the starter and its relay/solenoid either.

So just wait a moment for the light to go out. This is true for ALL diesels with glow plugs.
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post #14 of 15 Old 07-17-2019, 10:42 AM
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I am thinking my 850d glow plugs are shot. I have checked the relay and it is good. My question is it looks as though you have to remove the valve cover to change the plugs. Yes? Do I need to order a new valve cover gasket?
Thx
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post #15 of 15 Old 07-17-2019, 10:46 AM
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Quote:
Originally Posted by Christo View Post
I am thinking my 850d glow plugs are shot. I have checked the relay and it is good. My question is it looks as though you have to remove the valve cover to change the plugs. Yes? Do I need to order a new valve cover gasket?

Thx


You might consider starting a new thread. Your question will receive much greater exposure.

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