TC33D #5 Fuse

[SteveInMD]

I blew out my #5 fuse again (the safety interlock circuit). I've been through this before, and I have one of the incorrect owners manuals which says #5 should 7.5 amp. I have a 10 amp fuse in there as it should be, however when I went to start the tractor today I got nothing. I went right to the fuse block and found the problem. My question is..I've heard of a number of people with the same issue, so why does this fuse keep burning out? Has anyone found the problem with the circuit?

 

[LarryD]

I think you already know WHY the fuse keeps blowing, to many amps. The question is what's causing it.

You could have the battery checked, look for bad connections or a maybe short. Lots of possibilities here.

How about disconnecting all terminal blocks you can think of and jumping across them. Then add each one back into the circuit individually and see when the fuse blows, just a thought.

<font color="blue"> I've been through this before, and I have one of the incorrect owners manuals which says #5 should 7.5 amp. </font>
I have yet to blow any fuses or validate fuses to what the manual says, but your post is not the first to indicate a typo or smaller fuse. How did you determine the fuse was incorrect? It think it would be handy to know the correct fuse to use. Is there a written source for proper fusses as opposed to the owners manual?

 

[jinman]

Steve, you are the first person I've heard of to blow a 10 amp fuse in that circuit. /forums/images/graemlins/confused.gif I put a 10 amp in my tractor and that cured my problem; however, my tractor is different and maybe just enough.

I think I'd start by checking the battery voltage when the batter is overnight cold. If it's below 12 volts, I'd be suspicious that I had a cell going bad. If the battery is not supplying full voltage, that has been responsible for the blown fuse in several Class III models. The other thing to check is corroded terminals. That can also cause intermittent surges and problems. Other than that, I don't know what to suggest. My tractor is a 4-cyl and has 4 glowplugs. You'd think four would pull a lot more current than the three in your 33D, but maybe there is just that much difference in the load in other areas or the type of glowplugs. My glowplugs only stay on for about 10 seconds and then go off. That's when I start the tractor. I try to consciously not start the engine while the glowplugs are preheating.

Good luck finding your problem. Intermittent electrical problems are the pits. /forums/images/graemlins/tongue.gif

 

[DieselMonk]

Hi Jim!
"I try to consciously not start the engine while the glow plugs are preheating."
Sure you shouldn't do that, but I have to disagree with you there (and that is very rare what I read so far from your posts). I don't think the glow plugs (and other accessories) are getting any juice, while you are actually cranking over the engine (or at least are not supposed to). That would flatn the battery very quickly and the fuses won't like that either. Besides that the wiring would have to be very heavy.
I think his problem is like you mentioned before either the battery itself, the battery terminal contacts,chaffed / half broken wires or bad contacts some were.

Cheers!

Max

 

[SteveInMD]

LarryD - Some of us got an incorrect owners manual, which says the #5 fuse is for the turn signals and should be a 7.5 amp fuse. It was corrected by NH with a new version of the owners manual saying the #5 should be 10 amp fuse and is for the safety interlock circuit.

jinman - You are probably right, my battery was low. It had been quite a while since I last started the tractor. I hadn't considered that the lower voltage would increase the amps running through there.

Thanks....

 

[jinman]

</font><font color="blue" class="small">( ...I have to disagree with you there (and that is very rare what I read so far from your posts). I don't think the glow plugs (and other accessories) are getting any juice, while you are actually cranking over the engine (or at least are not supposed to). That would flatn the battery very and the fuses won't like that either. Besides that the wiring would have to be very heavy. )</font>

Max, I would not just answer your question based on what I thought without checking my manual. Now I've done that and I stick by my original post. If the glowplug timer has not run down (only 4 to 5 seconds on a deluxe model, 10 seconds on an economy model) the glow plugs are still powered when the key switch is turned to start. There is an internal bus bar between position 2 and 3 on the key switch to ensure power is available to the glow plugs until the glow plug timer stops (times out).

Yes, the wiring is heavy, and yes this puts a load on the battery which is exactly why I do not start the engine until the preheat cycle is over. The battery feeds the starter directly through the solenoid switch and the glow plug relay connects the glow plugs to the main supply 40 amp circuit, but they will both be connected if you go to start immediately with the key switch.

Not only have I checked the circuit diagram, but I'll also watch my glow plug light the next time I start my tractor and I'll purposefully go to start before the cycle is over to see if the glowplug light immediately extinguishes. My guess from the circuit is it may dim, but not go out. We'll see... /forums/images/graemlins/smile.gif

EDIT: Confirmed... I checked on my tractor before leaving for work this morning. At least on the Class III Boomers the glow plugs will stay energized while the starter is running if the glow plug timer relay has not timed out. That means if you don't wait until the light goes out, you will load the battery with both the glow plugs and the starter. On a weak battery, that might make a difference.

 

[DieselMonk]

Hi Jim!

I guess I do owe you an apologee! Went out in the garage this morning with my DC current clamp in my hand and started measuring on my car and on the tractor. /forums/images/graemlins/grin.gif Interesting indeed. The tractor glows it's plugs (and all accessories can be on too!!!) while cranking (like you said), but my VW TDI does not (all accessories are off). Maybe that confused me. Funny, the things one can assume once not using the tractor for a while. /forums/images/graemlins/blush.gif Gee... always something. One thing for sure: One wants to have a healthy battery on these tractors!

Cheers!

Max

 

[djradz]

I know this probably doesn't affect the #5 fuse discussion here, but all should be aware that the connection of the cable from the battery to the strarter, at the starter, is prone to corrosion. I believe this is primarily the fault of moisture, if your tractor sits outside or is washed, collecting in the red rubber insulating cover/boot over the screw and lug at the starter. The boot is like a cup and collects water, with no where to go. Corrosion soon follows.

 

[jinman]

</font><font color="blue" class="small">( I guess I do owe you an apologee! )</font>

Not at all! Every time someone asks a question or questions something I say, I end up learning more in the process of making sure my assertion is correct. I suspect you and I and several other TBNers learned something from your questioning my statement. That can never be bad nor requires an apology. /forums/images/graemlins/smile.gif

 

[DocHeb]

Jim

Are the Starter and the Glow Plugs on the same fuse in the Class III? If so, simultaneous GlowPlug/Starter use may be causing the nefarious Class III Fuse #2 problem.