TN75 - blowin' fuse and...

yeehaw · Feb 22, 2009

Finally found a tractor (after how many months days hours years of searching...) in my opinion a nice little rig - tn75 4wd with loader and around 1000 hours...found it at a JD dealer and there is not many NH dealers locally...they just wanted to get rid of it....here's my question..
when i got it neither the fuel gauge or the temp gauge were working (nice rig u say?) - all we did was replace the fuse before it left the dealership and - bingo - workin' just fine (back of my mind I was thinking that something had to make the fuse blow - 04 model)...
anyway...was using the tractor this weekend and (first 30 minutes - to hour of work) and bang- the fuse blew (here's the kicker) the battery light came on also - and stayed on until I shut the tractor off...about 5 minutes or so...(tractor ran fine until I cut it off)..
it then started right back up with no problem - and no battery light....
assume a short somewhere - yet - this seems to be a little odd - especially with the light coming on at first - but then not staying on all the time
(I always thought that light stood for "low battery" - but the manual says "battery charging system warning..."

thoughts?

jimg · Feb 23, 2009

I think Id try to resolve the fuse problem first as it seems the simplest and most straight forward (at least at fiest glance) to trouble shoot. Perhaps the battery issue is somehow dependent (being casued by) the former?

Have you attempted to find a short in the system? Id be interested to see how this all goes.

yeehaw · Feb 23, 2009

that is what I figured (short then battery light...)
Havent had a chance to take a look at it yet - probably sometime early this week...thought someone might have a idea before I started tracing wires...

ought to be interesting as I am more mechanically inclined than electrical <bssst> - yet I intend to have a go of it...

jimg · Feb 23, 2009

Well, best of luck running the problem to ground. I would be really interested in what you find. Would you keep us posted?

ETA: Do you have a schematic to work from?

yeehaw · Feb 23, 2009

I have some of the diagrams off of the NH parts website which are "somewhat" helpful...(if you know of some better diagrams - i would be much appreciated)...
thanks

jimg · Feb 23, 2009

I dont but I wondered if you bought the electrics manual for the TN. I suspect itll contain good infos about whats what. If it was me Id look for the obvious and then if that didnt turn anything up Id get the manual.

Gator6x4 · Feb 23, 2009

Start by checking the wiring around the alternator. The battery light coming on in my opinion indicates a problem with the charging system. You could have a short in the charging wiring allowing excessive voltage to enter the instrument panel components and the fuse is blowing as protection.

mojoinco · Feb 27, 2009

Sounds suspiciously like a short (the blown fuse) and possibly a ground issue (likely related) that is turning the charging system lamp on. Sometimes referred to as a ground loop.

Often components have 'shared' (sorry, poor choice of words, can't think of a better way to describe this) components. For example, many manufacturers (Honda was doing this in the early 70's) have a hot component (example, horn) that has a grounding switch. Versus having a hot side to a switch, with the ground running to/through the component.

An example of a ground loop is when you have a trailer that you know is wired correctly and all of a sudden the blinkers are flashing on the opposite side. It will always be a grounding issue on the device (lamp) that was supposed to be flashing (that's why you want to run a ground to EACH) lamp and to ONE point on the frame (and wire directly to the trailer connector).

yeehaw · Mar 7, 2009

How many fuses can one blow while trying to diagnose an electical problem? Over under for me was nine... quick summary...as i think i have the problem fixed...
1. first time i thought i had it fixed i found a bundle of wires going up into the bottom of the ROPS (or frame of rops) and the "main" wire was snug against the corner - the bare wire i thought i saw ended up only some dirt - lesson learned - thumbnail got the dirt off

2. I thought this one was it...there are numerous large groups off wires coming out from the fuse box into the engine area where they splice off...(most have large connectors before they splice off) - right before one of the connectors one of the wires was resting on a small piece of metal tubing (on the engine)...even though the wires were wrapped in tape (right at the end of a rubber protective section) it had rubbed through the tape and through one of the wires. after fixing this one - another 10 amper down drain.....and i was actually heading back to the barn with smile....

3. yet when it blew the last time the gauges acted funny when i lifted up out of the seat...huh. After removing the seat (yes - taking the cushion off) - a wire underneath the seat had been "cut" against a bolt under the seat and was shorting against the seat (wonder the seat hadn't caught on the seat on fire as i tested it and a pretty good spark occurred - talk about lighting a fire under...) anyway i digress...
after fixing this one it seems to be working - so we shall see....and to think I was sitting on the problem all along...