TZ25da keeps blowing 20amp fuse...

99SVT · Oct 21, 2018

And, this fuse controls the alternator, charging circuit, headlights, taillights.

Does not seem to be any rhyme or reason for it blowing... I just get on it one day, and it does not start. I jump it off, let it run for a bit, turn it off, will not start back up. Check fuse... it is blown. New fuse, no issues, until it is blown again.
Cables are good, alternator seems to be charging (when fuse is good). I never use the lights.

Very confusing for me... anyone have any ideas?

99SVT · Oct 21, 2018

Well, narrowed it down.... sacrificed a fuse, and turned on the lighting, and the fuse blew. Now just have to find out what is causing it, in that system. Dealer had the operating platform off a year or so ago... maybe they plugged something in wrong. &#55358;&#56616;

Ford850 · Oct 21, 2018

Could be a pinched wire.

jaxs · Oct 21, 2018

I can't tell you what's blowing the fuse but I can help you find it if you are willing and able to spend some time crawling under,over and around the tractor. What I'm saying is I don't do well telling owners what they should have their dealer look for.

99SVT · Oct 22, 2018

Oh, dont worry... I will be doing the labor on this, and have no problem crawling around on this... was just looking for a place to start. I am going to unplug all the rear lighting connections, and see what happens.
I really dont want to have to pull the operators platform off. &#55358;&#56616;

jaxs · Oct 22, 2018

You stated in post #1 " this fuse controls the alternator, charging circuit, headlights, taillights." I seriously doubt fuse control's alternator but there's a slight chance it does serve something in addition to lights so if testing light circuit fail's to find problem it might be necessary to look elsewhere. Since fuse only blow's when lights are used, I believe the fuse only serve's lights so that's where we start.

Ok,you can use a test light or buzzer with alligator clips on leads for hands free convenience. Before you begin,familarize with your light/buzzer. On your car/truck or another tractor,remove taillight fuse and clip leads to each side of fuse slot and turn vehicle light switch on. Note brightness or volume then move leads to battery posts and note difference in volume/brightness. That subtle difference in brightness/volume is key to finding the short circuit that blow's fuses. Put clips on tractor light fuse slot,tester should not glow. Turn tractor light switch on and tester should glow at full brightness/volume(if indeed there's a short circuit in lights). Begin unplugging lights as you mentioned in post #5. When and if light go's out or drop's to half brightness/volume,the short is DOWNSTREAM from there. If volume/brightness hasn't dropped or gone off after all plugs are disconnected,leave everything un-plugged and move to next step. Jiggle,push and pull wires until tester dim's or go's off. Any questions? Good luck.

99SVT · Oct 27, 2018

Ok, traced it down, that fuse only blows when high beams are put on. So, until I figure out what is causing this... no high beams.

Checked both bulbs, and they are good. Might be switch issues.

gimmodog · Oct 27, 2018

clean the light grounds and any wire connections going to the lights and relay. A bad connection will cause it to draw excess current trying to get thru the bad connection therefore blowing the fuse. coat the connections and bulbs with dielectric grease. this will slow down the corrosion and bad connections. If you did not buy this new it possible that the fuse is undersized by a previous owner and you keep replacing with the same undersize fuse. Check to be sure.