# New holland tc40 glow plug



## Ironeye

Guys the glow plug just randomly failed where is it and what model of glow plug do I need thanks


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## sixbales

Howdy Ironeye,

Most likely your problem is with your glow plug relay, or your glow plug timer. I found the following post written by *jinman* on the TBN forum. Here is what he said:

*"I've attached an illustration that should help you. The red box is around your glow plug timer. Item #10 is the glow plug relay, but most often it is the timer that fails. This diagram is from the HST model tractor, but the relays for the glowplugs are in the same place on your tractor. You can buy the timer from your NH dealer for around $70, but a couple of people have said that they took the cover off and found a broken wire inside that was repaired fairly easily and saved them the price." *

PS: I learned that *jinman* passed away this year. He lives on through his posts. RIP


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## EdF

How old is your battery? If it is old, put some jumper cables on it from a good battery to see if that resolves your problem. Glow plugs pull a lot current, and your battery may not be up to the task.


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## sixbales

Ironeye,

Do check the battery, to be certain that it's not the problem.

*jinman* also recommended that you replace the New Holland glowplug timer with a surplus Kubota timer to save cost. You can find these timers on ebay by searching for Kubota NGK glowplug lamptimer S81NL P/N 15694-65990. Here is his explanation:

*"The only differences between the kubota timer and New Holland's is the length of the glow and price. The contacts and electrical connections are identical. The NH timer is designed for fast heating glow plugs and has a 5-7 second cycle. I think the Kubota cycle is 10 seconds. . . no big deal. I have two Kubota's for spares, but have not tried them, but others have successfully substituted them. The timer does not supply current directly to the glow plugs on our tractors. It only energizes the high current relay.

BTW: Kubota charges over $60 for that relay at a dealer. It just goes to show you what a markup there is on these parts. I have replaced $75 relays on my NH TLB with a $9 part from Grainger that is an exact duplicate except for mounting. My cheap relay came with a tab for mounting with a screw. Otherwise, there is no difference. Evidently there was some excess Kubota inventory that ended up on eBay. I found glow plug timers for just over $10 each and that included shipping. The Kubota kit even comes with a glow plug lamp, but of course, you have no use for that on the New Holland. It also comes with mating connectors and contacts. It's one heck of a deal. The next time I have my cowling off, I'm gonna swap out the relay just to test it, but I can see no electrical difference between the two." *


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## Ironeye

thanks for the help the tractor was bought about a year ago so im asuming the battery is a year to two years old (its shiny) so the battery should not be a problem also thanks for the blueprints "Sixbales" that should help alot so thanks to all and merry christmas!!!!


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## kr1967

*Tc40d glow plug*

Thanks for the tip, fixed my problem changing the timer! :


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## IsWorkahobbie

I'm having similar issues with a NH TD24A thanks for the info.


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## Rocky Knoll

Thanks to jinman (RIP) and sixbales. I found a Kubota timer module on ebay for less than $25. Same manufacturer and pinout as OEM and works great.

I thought I would share my experience diagnosing my issue since so many others have so generous with their info.

When I touched pin 6 on the timer connector (brown wire from the relay) using a grounded test light with the key on, it completed the ground path for the relay control circuit so the relay closed. You could hear it snap and the dash light came on steady, so that confirmed the relay circuit in my mind.

So after confirming 12V at pin 4 (the white wire of the timer connector, key on) and ground on pin 3 (Black wire) that pretty much left the timer module.


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## PabloRN

FYI- this discussion was very helpful in fixing the glow plug problem on the NH TC40 tractor I own. What i had trouble realizing was that the "relay" was different from the "timer." So, when I finally understood that I was able to pull the "relay" and take it to the local auto parts and find a replacement ($9) and that fixed the problem. Thanks, again. P.S.


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## Scott Cooper

I have a 2001 New Holland TC 40. I noticed my glow plug light was doing the same thing as all of yours has. staying on, flickering etc. Then all the sudden it went out for good. I replaced the lamp timer, or glow plug relay as it's called and still nothing. Does anyone here think it's the glow plugs? I've looked at all the fuses under the dash and when I put the new relay in all the connections appeared clean. I'm not sure where eals to look at this point. Other than to call the dealer.


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## BigT

Scott,
It's not the glow plugs. It is my understanding that there is 1) A glow plug timer relay, and 2) A glow plug relay. The timer relay actuates the glow plug relay, which in turn applies power to the glow plugs. These are common failure items, your dealer should have plenty in stock.

Read post #2, by sixbales, in response to the original question.


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## Scott Cooper

BigT said:


> Scott,
> It's not the glow plugs. It is my understanding that there is 1) A glow plug timer relay, and 2) A glow plug relay. The timer relay actuates the glow plug relay, which in turn applies power to the glow plugs. These are common failure items, your dealer should have plenty in stock.
> 
> Read post #2, by sixbales, in response to the original question.


Yes sir. Thank you for the reply.

That`s the part I replaced. It's the glow plug timer. Actually says lamp timer on the new part and the old one as well. So if there is a glow plug relay. Where is it and what does it look lke?. I've already replaced the part in Jinman`s illustration. Sorry to hear of his passing.


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## Scott Cooper

BigT said:


> Scott,
> It's not the glow plugs. It is my understanding that there is 1) A glow plug timer relay, and 2) A glow plug relay. The timer relay actuates the glow plug relay, which in turn applies power to the glow plugs. These are common failure items, your dealer should have plenty in stock.
> 
> Read post #2, by sixbales, in response to the original question.


My previous question was answered by looking at item #10 on the illustration. I'll try that and let you know. I just had the tractor at the dealer for about 2 weeks back in October for other issues. The flow plugs were working at the time. Thanks again for the information!!


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## Scott Cooper

BigT thank you for referring me back to the illustration! My problem turned out to be item #10. The glow plug power relay. The dealer had one for $24. I didn't seem to be able to find one online and I needed it sooner than later though. Fires right up after I cycle the flow plugs a couple times when it's really cold.


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