Glow Plug Timer control units

[Williy]

No 555 timer chips on the pc boards??

willy

 

[tc40da-rg]

I am so thankful for this Forum and all of the great folks posting herein! This thread is getting some years on it, but it is still providing very good information. My sincere grat to all the contributors.
My 2004, New Holland TC40DA has been giving me electrical anomalies pretty much since the day I bought it (in 2009). At present, it has been almost a year since the tractor cranked! (There’s lots of reasons why I have not been able to concentrate on getting it running again, but attempting to stay with it now.)
I found this thread while researching for all the possible reasons why this thing refuses to do anything but “click” when the key is turned on. When you turn it to start, nothing at all happens. I have exhausted all “the usual suspects“ — battery cables and terminals, starter, fuses, relays, safety switches, broken (and rat chewed) wires, ignition switch, etc. so, I find myself going down rabbit holes now. I should also add that I get confused and lost when electronics gets past “plug it in.”
I will start by saying that this tractor has been the hardest to cold start of any diesel I’ve ever owned; and I wonder if the glow plugs ever worked since I bought it at five years old. I’m thinking that it couldn’t be a truly bad thing for me to just go ahead and order new glow plugs, timer relay and control (relay?), considering its age, but I really can’t afford to just throw money at it either. So, my first question would be, Can the glow plug system cause a no start problem or not? Is it possible to pull the glow plugs and “service” them myself (believe it or not, I do have some DIY/mechanical skill.).
I’ve read in this thread about taking the timer apart, but honestly, I would have no clue what to look for or do once inside. What I haven’t ascertained from the thread is whether or not I can safely/successfully replace the original “NGK S81NF” with the S81NL(-1 or -2) without further issues?
Granted, the glow plug system is likely not the reason the tractor won’t start. But I figure, once it IS running, it will at least start at 40° without having to build a fire under it.

 

[koshari]

I am so thankful for this Forum and all of the great folks posting herein! This thread is getting some years on it, but it is still providing very good information. My sincere grat to all the contributors.
My 2004, New Holland TC40DA has been giving me electrical anomalies pretty much since the day I bought it (in 2009). At present, it has been almost a year since the tractor cranked! (There’s lots of reasons why I have not been able to concentrate on getting it running again, but attempting to stay with it now.)
I found this thread while researching for all the possible reasons why this thing refuses to do anything but “click” when the key is turned on. When you turn it to start, nothing at all happens. I have exhausted all “the usual suspects“ — battery cables and terminals, starter, fuses, relays, safety switches, broken (and rat chewed) wires, ignition switch, etc. so, I find myself going down rabbit holes now. I should also add that I get confused and lost when electronics gets past “plug it in.”
I will start by saying that this tractor has been the hardest to cold start of any diesel I’ve ever owned; and I wonder if the glow plugs ever worked since I bought it at five years old. I’m thinking that it couldn’t be a truly bad thing for me to just go ahead and order new glow plugs, timer relay and control (relay?), considering its age, but I really can’t afford to just throw money at it either. So, my first question would be, Can the glow plug system cause a no start problem or not? Is it possible to pull the glow plugs and “service” them myself (believe it or not, I do have some DIY/mechanical skill.).
I’ve read in this thread about taking the timer apart, but honestly, I would have no clue what to look for or do once inside. What I haven’t ascertained from the thread is whether or not I can safely/successfully replace the original “NGK S81NF” with the S81NL(-1 or -2) without further issues?
Granted, the glow plug system is likely not the reason the tractor won’t start. But I figure, once it IS running, it will at least start at 40° without having to build a fire under it.

start with the basics, glow plugs are basically resistors, you will need a multimeter and sadly you will need to learn how to read it,
from there you will understand terms lie resistance, current flow and voltage drop , they are all related, in my experience most issues are from a poor circuit supplying the plugs, from wiring connectors right up to the glowplug itself, they are all cumulative in reducing the current flow and therefore the ability of the plug to heat the fuel cavity. your post definitely indicated the glow plugs are not delivering optimal heating, do you have a pigtail in the circuit?? reading the pigtail can tell you a lot.

 

[koshari]

On the 6 year old topic....glow plugs, I read a few days ago that glow plugs in general have a limited life so timing is important...don't run longer than necessary. With that said, older plugs took about 30 seconds to operate adequately for cold temps, not the coldest but cold temps. Currently designed plugs operate in single digit seconds. I just bought a 2020 tractor, thinking the GP timer had malfunctioned as compared to my other tractors with the newest being 2016 since with them, the heater and indicator would stay on the longer period. The new one turned off just a few seconds after illumination as did the plug...you could hear the relay clicking on a cold day. Well on a colder day I tested it and they stayed on for a longer period but still less than 10 seconds. So I quit worrying about that.

they have a limited life but so did the pyramids of gaza , its all relative, if they are still heating they are still good.

 

[tc40da-rg]

... your post definitely indicated the glow plugs are not delivering optimal heating, do you have a pigtail in the circuit?? reading the pigtail can tell you a lot.

I’m not familiar with a “pigtail” nor how one is read.

Thanks for your great response. I have a VOM and can use it. Also have a tool that inductively reads/follows current in wires. It has proved to be invaluable for the New Holland.

I think my biggest question for the post was whether or not the NGK S81NL relay is a proper replacement for the NGK S81NF ?

 

[koshari]

I’m not familiar with a “pigtail” nor how one is read.

Thanks for your great response. I have a VOM and can use it. Also have a tool that inductively reads/follows current in wires. It has proved to be invaluable for the New Holland.

I think my biggest question for the post was whether or not the NGK S81NL relay is a proper replacement for the NGK S81NF ?

pigtail is slang for a inline indicator that glows red when glowing, its generally found on older machines, if they are glowing a nice red when glowing they indicate good current ( and therefore good heating) . use that DMM to measure voltage across the glow plugs while glowing, the aim is to have as much voltage drop across the plug rather than in the feeder circuit. this is why nice thick short wires with minimal joins to the glow plugs help, also if you can attach the feeder cable to the center of the glow plug bus ( local cable that attaches all the glow plugs) as opposed to an end, this means that the current is reduced in the first segment reducing copper losses. and lastly ensure there is good contact to the plug itself, for example one of our mowers was not glowing well and turned out the washers above the securing nuts has oxidisation, i took them off, sanded them back, places silicone grease on them and snugged them back up.

 

[tc40da-rg]

pigtail is slang for a inline indicator that glows red when glowing, its generally found on older machines, if they are glowing a nice red when glowing they indicate good current ( and therefore good heating) . use that DMM to measure voltage across the glow plugs while glowing, the aim is to have as much voltage drop across the plug rather than in the feeder circuit. this is why nice thick short wires with minimal joins to the glow plugs help, also if you can attach the feeder cable to the center of the glow plug bus ( local cable that attaches all the glow plugs) as opposed to an end, this means that the current is reduced in the first segment reducing copper losses. and lastly ensure there is good contact to the plug itself, for example one of our mowers was not glowing well and turned out the washers above the securing nuts has oxidisation, i took them off, sanded them back, places silicone grease on them and snugged them back up.

Thanks again. Very much appreciated. I’m afraid I will have to spend a little time deciphering some of that, but will work on it.