TZ25DA

[engineer bill]

My TZ25DA has blown a 25amp fuse and its the one that when you turn the ignition key on runs the fuel pump, instrument panel, safety start circuits, and HST cruise control.

inserted a new 25 amp fuse and it blew immediately! any suggestions?

Bill

 

[Jerry/MT]

My TZ25DA has blown a 25amp fuse and its the one that when you turn the ignition key on runs the fuel pump, instrument panel, safety start circuits, and HST cruise control.

inserted a new 25 amp fuse and it blew immediately! any suggestions?

Bill

I'd start looking for a short in the very circuits you mentioned..

 

[jinman]

Bill, I can't see 25 amps needed for all those things you listed if they are taken separately or together. All those things would probably pull much less than 8 amps normally. Is the 25 amp fuse your main fuse that feeds other fuses? That is just a huge fuse for individual circuits. Even lighting fuses are normally no more than 15 amps.

I obviously don't know the TZ25DA, but that seems to indicate a bad/shorted key switch. Normally a 25 amp short produces some burned wires or smoke. That's a lot of current for normal tractor wiring. That much current is normally fed on 10 gage or 12 gage wire. The wiring in my tractor is mostly 16 or 18 gage that would fry with 25 amps.

EDIT: I checked the parts diagram and found a 25A and 20A fuse in addition to the 40A main fuse. I don't know what the 25 amp fuse feeds, but could it also feed glowplugs in addition to what you've listed? If it does, I'd disconnect the glowplug lead and replace the fuse to see if it still blows. I just can't see anything you listed that could ever use 25 amps. There must be additional loading. BTW: My tractor's glowplugs (4) are wired with a 12 gage power lead. The main power lead going from the ignition to the fuse bus is 10 gage wire. The wire from the 40 amp main breaker is 6 gage.

 

[engineer bill]

Just started tracying things tonight, it is in fact a #12 wire on a 25 amp fuse, and i am tracying out items as previously mentioned. its a slow process. I called the dealer today and spoke to the shop mechanic and he mentioned that he has worked on one with the same problem, and found a pinched wire on the frame, but he could not remember exactly where? he did suggest looking at the HST cruise because it does have a large wire and when in use a large current draw for a magnet.
It was running fine and it died when it bounced once on a drop off the pavement.
The fuse is fed directly from the key/switch and all is well to the fuse block. so it has to be one of the previous mentioned items.
Ok, back to the barn. will check in later

 

[jinman]

Bill, that cruise control magnet cannot draw current until the cruise control switch is placed to "ON." It could be shorted and there is no reason to blow the fuse as soon as you turn on the key switch. The cruise magnet should be around 12 ohms and that means it pulls only slightly more than 1 amp. If it were pulling 25 amps, it would go up in smoke and stink up the whole area. I think you likely have a shorted wire, but I don't think it is any component unless it's some high current circuit like the glowplugs. Which of your fuses feeds the glowplugs? My glowplugs feed directly off the 40 amp fuse, but the control relays are fed by normal low current circuits. Again, nothing you listed should ever approach a 25 amp load. I think there is something you are missing that is on that circuit. BTW: Owners Man'ls and Repair Man'ls are notorious for leaving out things. We have a fuse #2 problem on our larger tractors and nowhere in the manual does it say that Fuse #2 feeds the starter solenoid. I had to find that out by reading the schematic. Just sayin'. . . Good luck!

 

[engineer bill]

Jinman,

The 25 amp fuse blows immediately when turning on the ignition switch, so at this point i would not have activated the glow plugs, it would be one more movement cw to the right, then the next cw movement would be the starter.
I was only checking the HST cruise as it was an add on and I thought maybe that would be the first place to check the supply to the switch. I have checked out the Cruise feed wires and they are good.
So I am guessing next is removing the steering wheel, hood, etc to get at the ignition switch and fuel pump. Tomorrows project

 

[jinman]

Bill, do you have an owner's manual? If you do, it has an electrical schematic in the back. If you could scan that and post it, I could sure help you more, but I've reached the end of what I can suggest based on SWAGs. Also, do you have an ohmeter? You can disconnect your battery power and then hook an ohmeter on the lowest ohms scale to the output of your 25 amp fuse and turn on the key. The ohmeter should go to zero ohms if you have a short. Next, start disconnecting things until the ohmeter shows higher resistance. The last wire you disconnect before resistance goes up is your culprit.

 

[barbqranch]

This is just a guess, but I would suspect the key switch.

 

[engineer bill]

ok here is the update:
i have traced the short to the idiot panel board above the steering wheel, and it has a dead short. working my way thru that board now. I did remove all the bulbs and the dead short went away. so now I will need to proceed to determine if its the board or a which bulb or socket is the culprit? just called the dealer and he said that he can get the complete board and guages by mid to late next week. I will try to determine what in the panel is blown.:confused2:

 

[engineer bill]

well board ohm'd out ok so now i am past that and its appears that it's on the oil pressure side of things. more digging testing and researching needed!

update: Oil pressure sensor sending unit is shorted to ground? I have now disconnected it and the tractor will start and run. will order the new one on monday, otherwise this tz will sit till its replaced for saftey of the unknown oil pressure.

now to put everything back together.