Blowing 7.5 fuse on my TC45

[itsmatt]

I've got a TC45 with about 300 hours on it. A week ago the front headlights, tach and fuel gauge suddenly went out. I took the two screws off the instrument panel and found that the 7.5 amp fuse had blown on it. It had been running fine all winter/spring. I have hooked up the finish mower now to cut the fields and replaced the fuse tonight. I started up the tractor, engaged the PTO to get the mower deck going and went to put it into fwd and it blew the new fuse as well.

I am a bit confused as to why his would start happening. Any ideas?

Thanks,

Matt

 

[jinman]

Matt, are you talking about fuse #4? That's the one in the center of the fuse block. There are three 7.5 amp fuses, so before I give you any advice, I need to know for sure which fuse was blowing. My guess is #4 because it is for lighting control and the instrument panel. It could be that your light switch on the dash has a short or has water in it. The power to the lights does not come from the 7.5 amp fuse, the power from this fuse just energizes a relay for the lights. Power from the 7.5 amp fuse also runs your engine temperature gage and sending unit on the engine. Is the wire possibly disconnected and touching ground somewhere? Also, you have to consider that some critter like a mouse may have made a winter home in your tractor and chewed some wires. If you replace the fuse and it blows right away as you say it did, you need to look for the cause.

Finally, you could have a bad relay, but I would check the headlight switch and the wiring first. Remember, it will do no good to unplug lights. They are controlled by this circuit, but the current to light your lights comes from the 15 amp fuse on the far right of the fuse module.

 

[itsmatt]

Jim,

Thanks for the information - I'll go back and check this out.

Matt

 

[djradz]

How about a light bulb that has burned out, but shorted in the process. I've had this happen a few times and it's very common on auto turn signal lamps, which are quite similar.

 

[jinman]

Duane, the only lights the #4 fuse powers are the little-tiny ones in the dash panel itself. If he disconnects the dash and the fuse quits blowing, that could be the source. All the other lights are powered through the 15 amp fuse (#7). The 7.5 amp fuse supplys power through the light switch to the coil of a relay. The contacts of that relay close to illuminate the lights. That pretty much isolates the 7.5 amp fuse from the headlights/tail-lights unless the relay is shorted internally. Since the headlight switch is exposed to weather, I think it's far more likely that it's seal leaked water inside or that some critter has chomped on his wires this winter. /forums/images/graemlins/tongue.gif

 

[itsmatt]

Jim,

Yes, it is the #4. I looked at the wires and didn't see anything unusual, though I must admit, it was tough to see really well down in there.

I stuck another 7.5 in there and here was what happened:

I purposely left the light switch off and started the tractor as normal. The rpm and fuel gauge were working as usual, as was the hour counter which stopped working the other day - it must run off of that too, I suppose.

I have a cab on the tractor that has front/back spots on it. I cut a little grass with just those lights on tonight and then a little later, I flipped the headlights on while I was moving forward. everything was fine. I flipped the headlights off again, put it in reverse and then flipped the lights on again, and once again everything was fine. Then, I left the headlights on, put it into neutral and when I went to put it into forward again, that is when it blew the fuse.

Looking back, this was the scenario that blew the fuse the other night too. I had the headlights on but was in neutral and when I went to put it into forward, that is when it blew as well.

Any ideas?

Matt

 

[PineRidge]

How long have you had the cab and who tied the lights into the electrical circuit?

 

[itsmatt]

</font><font color="blue" class="small">( How long have you had the cab and who tied the lights into the electrical circuit? )</font>

The cab was put on when the tractor was bought by my wife's dad maybe two years ago. I don't really know who wired up the lights. I believe it was the people who sold him the tractor. Unfortunately, he died this past September and he was a wiz at tractors and most things. I'm limping along trying to learn as I go. It has been a challenge.

Matt

 

[jinman]

Matt, you need to do a quick check to see if your cab lights are wired to the proper circuit. Fuse #3 is supposed to be a 10 amp fuse that is for turn signals and rear work lights. With your cab lights on, pull that fuse and see if the cab lights go out. If not, you need to get your cab lights rewired. Fuse #6 is also a 10 amp fuse for your emergency flasher circuit. It may have been wired into the rear lights also. Fuse #7, 15 amps, is for the headlights only.

I think you found your problem but you just don't know where it is happening. I believe you will find that your selector is rubbing against a bare wire when you go from forward to reverse. It probably took this long for the insulation to wear through or be pinched. I don't know what to tell you except you will have to trace every inch of the selector connections and see if it is rubbing against a wire. There is absolutely nothing electrical I can find to indicate any connection between the gear forward and reverse shuttle and the #4 fuse. It almost certainly has to be a chafed wire. Unless it is a coincidence relating to how long your lights were on, I'd bet something has rubbed through. Happening twice at the same action really tells you this has got to be the source of the short. I'll be very surprised if you find it is something else. I think it's time to remove your cowling and do a detailed inspection.

 

[PineRidge]

Matt I'm betting that the lamps draw more amps than the fuse that is protecting them. There was another member here that also had a cab professionally installed and the tech tied into the wrong circuit on his rig. As I recall the fuse would blow randomly but not when the lights were first energized.

I think to cover the bases that it would be easier and also save you considerable time just to run a new circuit of adequate size to your cab lights and see if your existing problem goes away.