Having trouble with my 30A fuse #5 blowing when in the glow plug heat cycle. Pulled the preheat relay and can crank over tractor all day without blowing fuse. Pulled NGK glow plug lamp timer relay and bench tested per previous threads and didn't light up at all with a test light - therefore suspect this is bad. Will this timer cause this 30A fuse to blow after a second or two of preheating the glow plugs? I verified power at the buss connection of the glow plugs for that timeframe until the fuse blows. New timer appears to be about $60-70 so wanted to make sure I didn't ruin it if something else was wrong. Looking at the wiring diagram it almost looks like this timer relay only controls the display light on the dash and doesn't shut off power to the glow plugs themselves. Does anyone have a better wiring diagram for this timer relay - NGK model no S81NF? Any better sources than the NH dealer for this part? Thanks for your help.
TC25D - Fuse #5 Blowing
- Thread starter gz07g2
- Start date
SteveInMD
Platinum Member
The original timers often go bad, but the replacement I put is has worked just fine. I think blowing the 30 amp fuse is a different issue. The ignition switches also burn up on these machines. I think the starting circuit needs to be modified to really fix it (but that's what I always say!) I have a diagram if you want it.
thclimer
Platinum Member
Steve, I'm in total agreement with you, the ignition circuitry for at least the TC33D needs some tweaking. Other than I have been very happy with my New Holland!
gz7g2, My original timer failed after a few years, I had a new one in for about a year without any issues. I also agree that your timer issue is probably not related to your 30 amp fuse blowing. Is your battery in good shape?
Tim
ironpen
Gold Member
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- May 16, 2006
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- tn75s, tc33d, mc35, gt65, 6640, 3010s, TS110, TS115, TN70, Massey 5470, Kubota F2690
May be of no help at all, but if my lights are turned on when I try and crank, it blows the fuse every time also. Probably not your problem, but for what it's worth. Good luck
George2615
Super Member
Not familiar with what your #5 fuse is for. I'm guessing for the glow plug circuit. If so and its not your timer or relay it is possible one or more of your glow plugs may be shorted causing a high current draw enough to pop a fuse. Check the glow plug resistance individually without the buss bar connected. I have a different tractor but had hard starting problems in winter and it turned out I had 2 of 3 bad glow plugs. One was shorted to ground, one was an open circuit, leaving only one working. If you have access to a DC amprobe you could clamp it around the hot wire that feeds the plugs and check current draw. If its close to 30A the plugs are probably at fault.
Willl
Elite Member
Can you post the wiring diagram ?
After more investigation this weekend using your suggestions, I tested each of the glow plugs but didn't really notice any difference by my meter. However, when I powered each individually one was blowing the 30A fuse while the other two hooked up individually and in parallel did not blow the fuse. Thus, I am now waiting on my dealer to get a new glow plug.
As for the glow plug timer, I'm sure its still bad but for $60 I'm going to go without for now since from what I can see it only controls the display light.
SteveInMD....If you have the wiring diagram available - I would like to see it.
Thanks for everyone's help/suggestions.
As for the glow plug timer, I'm sure its still bad but for $60 I'm going to go without for now since from what I can see it only controls the display light.
SteveInMD....If you have the wiring diagram available - I would like to see it.
Thanks for everyone's help/suggestions.
thclimer
Platinum Member
I can only speak for the TC33D; my recollection was that its glow plug timer does indeed control the powering of the glow plugs to pre-heat. If I'm remembering mine correctly when my timer failed on my tractor, it was hard to start, especially as it got colder outside.
George2615
Super Member
gz07g2,
Can't help with the exact schematic for your tractor but here's the one for my different brand and model tractor. The principles are the same though your wiring may be different. It should give you an idea on how your timer and relay connect to the glow plugs. You can test the glow plugs individually with a simple ohm meter. One probe to the top of the plug, the other to ground. The one you tested that blows the fuse is probably shorted to ground which would create a high current draw exceeding the fuse capacity.
Can't help with the exact schematic for your tractor but here's the one for my different brand and model tractor. The principles are the same though your wiring may be different. It should give you an idea on how your timer and relay connect to the glow plugs. You can test the glow plugs individually with a simple ohm meter. One probe to the top of the plug, the other to ground. The one you tested that blows the fuse is probably shorted to ground which would create a high current draw exceeding the fuse capacity.
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SteveInMD
Platinum Member
Sorry for the delay - I've had family in town and haven't been keeping up here.
Ever since I changed my starting circuit as in the attached diagram I've had no electrical problems at all.
Ever since I changed my starting circuit as in the attached diagram I've had no electrical problems at all.