TC29DA Main Fuse Blown and Fuse Block Melted - Help!

[bartonkj]

TC29DA. The 40 amp main fuse blew and melted the fuse block. Slot B of the ignition connector (12V Input terminal) also melted. The wire and wire coating are OK, but the plastic surrounding that particular wire melted. I tested the ignition switch and it passed all of the tests in the repair manual. A few months ago, the dealer replaced the starter, the battery, the water pump and a few other things, but I have put less than 10 hours on it (over 2 - 4 days of use a week or two ago) since the repairs. I can't afford the time or the money to have the dealer repair this again.*

Behavior before fuse blew:
I started the tractor last night and when I held the key in the glow plug position, the glow plug did not go out after the normal interval. I held it for several seconds to see if it would go out. It did not. I then started the tractor and the glow plug light went out and the tractor ran fine. I took a load of heavy trash to the end of the drive, set the parking brake and set the gear selector in neutral (the PTO was not engaged). The tractor was running fine as I was unloading the trash. I had the high beams on and I had the hazards on. Then it just died, but it wasn't just the engine that died: all the lights died too (I know, consistent with the main fuse blowing).

Questions:
A) Any ideas on what might have caused the fuse to blow, or what I should check next?
B) I assume I will have to splice in a 40 amp fuse block into the wiring harness? Please correct me if I'm wrong (the wires go into the harness and I can't tell where they go from there - I mean I think the wiring diagram shows 1 end going to a junction with the battery, the starter solenoid, and the alternator, but I don't have experience with wiring diagrams and looking at a diagram is very different from looking at the physical wires. Also the wires into the fuse block are very large, but I don't see other large wires). Where can I get a replacement fuse block?
C) Where can I get a replacement connector for the ignition switch?


*1) It is blocking my driveway, 2) The front end loader is in the down position, so I don't even know how they would load it on the truck, and 3) We are in the process of moving which makes for all sorts of other complications

 

[George2615]

The specs I read on theTC29DA show the alternator rated at 40amps. If you were parked with the engine at idle speed the alternator was probably not putting out enough amps to power the lights on high beam along with 4 ways flashing and overloaded the circuit. Just a guess.

 

[bartonkj]

The specs I read on theTC29DA show the alternator rated at 40amps. If you were parked with the engine at idle speed the alternator was probably not putting out enough amps to power the lights on high beam along with 4 ways flashing and overloaded the circuit. Just a guess.

And if that is what in fact happened, then that should mean there is no permanent short, just a temporary short that won't be repeated as long as those conditions do not happen again?

 

[Roadworthy]

You can try jacking up the loader then blocking or securing it in some manner in that position. It could weigh 600 pounds or more. You may be able to block the linkage in the up position or secure with tie down straps. The electrical is unlikely to be the lights and flashers running. Overcurrent there should simply have blown the fuse. This may be connected to your glow plug issue or not. I'd look for worn insulation on a wire next to the tractor frame somewhere. There could have been mice at work.

 

[thclimer]

I'm wondering if there was also a draw from his glow plugs, doesn't 40 amps from just lights seem like a lot? Even though the glow plug light eventually went out, I wonder if the glow plug relay was still supplying power to the glow plugs?

 

[bartonkj]

I'm wondering if there was also a draw from his glow plugs, doesn't 40 amps from just lights seem like a lot? Even though the glow plug light eventually went out, I wonder if the glow plug relay was still supplying power to the glow plugs?

If the glow plugs were drawing too much power is that more likely to be from the glow plug timer relay failing or a failed glow plug?

 

[5030]

You have a dead short to ground first off and secondly, replace the 'Molex' connector yourself. Dell Electronics sells them and so does Digikey and they are on Amascon as well. Your picture of the connector shows it to be filthy inside and probably high resistance and if there isn't a dead short to ground (causing the melted Molex connector), Then replace it. Not hard at all, you need to acqire that knowledge instead of paying someone else to do it. Really easy and... When you replace it, pack it with di-electric grease as well. Hope you are actually maintaing the unit also.

 

[thclimer]

If the glow plugs were drawing too much power is that more likely to be from the glow plug timer relay failing or a failed glow plug?

There are some variations for the wiring schematics, see attached. You mentioned that your main fuse was a 40amp. My TC33D uses a 30amp and the attached schematic's both indicate a 30amp, so I'm a little confused by your 40. My TC33D uses a glow plug timer/light relay #7 as well as separate relay #3 to power the glow plugs. When I mentioned "I wonder if the glow plug relay was still supplying power to the glow plugs?" I was thinking your tractor was similar to mine, however yours might only have relay #3.

Are you the original owner of your tractor? I'm only wondering because of the 40amp main fuse you have referenced.

Do you have a copy of its electrical schematic?

 

[thclimer]

I would definitely replace your main fuse with its appropriate size before trying what I'm mention below:
Since the weather is warm, if your issue is only with the glow plugs you could pull their relay(s) eliminating them from the electrical system and get your tractor started as you mentioned it was blocking your driveway.

There seems to be something a little intermittent with your main fuse blowing as you were able to start your tractor, then after a few minutes the main fuse blew. Maybe it had a "dead short" when it blew, but I don't think you could have started your tractor with it having a dead short.

 

[rjok]

We have a TC-33. I replaced the main fuse once in the 25 years we have owned it. Ours has a 30 amp fuse. We have to hold the ignition switch to preheat the glow plugs. If it was me, I would put a 30 amp fuse in the main holder and put the switch connector back together and see if it starts.If you have a test light or a volt meter you can test if the power to the glow plugs shuts off on it's own.
Rick

 

[bartonkj]

So an amazingly fortuitous thing happened. As noted in my original post, my tractor broke down at the end of my driveway. I was working on it yesterday evening to replace the 40 amp main fuse holder with an inline 40 amp resettable breaker switch. A man (Tom) who just retired as a mechanic from a local tractor dealer, was driving by and stopped. He asked what happened and I explained. He said he couldn't do anything then, but could come back tomorrow. I happily accepted. I finished installing the inline breaker last night. Although one of the fours wires in the connectior for the ignition switch got too warm and melted a little of he plastic, I deemed it still OK to reuse for now. I reassembled that, then turned the ignition to the glow plug heat position and the glow plug light went off at the proper time instead of staying on. I didn't try to start the tractor then.

Today, Tom came over and we went over the tractor together looking for any frayed wires or shorts. As best as we can tell, here is what happened. Oddly enough, even though the 40 amp main fuse was melted and the fuse connector was melted, the fuse never blew. Once Tom cleaned off the fuse blades enough to get a connection, he tested and there was continuity (this as not the first thing we did, btw, he had a thought after we talked quite a bit about what happened and what might have caused it). The starter had been going bad for a long time. It would only start intermittently, so I had to turn the ignition multiple times until it would finally catch. Tom suspected the bad starter cause a lot of heat to build up in the main fuse over time and it melted, but didn't draw enough amps to pop. There was still enough of an electrical connection to run the tractor until for whatever reason the night it broke down it finally had enough and the circuit was open due to corrosion on the burnt components rather than popping the fuse.

At the same time, there appears to be a problem somewhere with the hazard lights. When the engine is not running, the hazard lights work fine and the turn signals work fine. HOWEVER, when the engine is running and the hazard lights are on, they start flickering and don't work correctly. The problem is even worse when the headlights are on, too. We don't know what exactly is causing the problem, but I was satisfied with the situation for now. I just won't use the hazard lights (I can get by without) for the time being.