Possessed 4720 Cab

[orlo]

Hi:

A few months ago I had a weird issue. I went to start my 4720 in my
barn (heated - 50 degrees) and the dash lights flashed after I tried
to start it, flashed on/off, etc. Then went dead - No start and
the overhead light, headlights, everything was dead but sometimes
the lights would flash but That might have been the radio (see below).
(I charged the battery, etc. Nothing changed).

I had the JD dealer I bought it from in 2010 come down and take a look
at my expense for transp, etc. Had them do other things to my 2305 and
do some maintenance to make it worth my while. Of course when the tech
arrived it wasn't happening. He looked at everything suspect, grounds, connectors, etc.

Ok, I brought the tractor in from the outside Wednesday (The day before yesterady) AM before
a storm (I only had it outside since I needed room to work on stuff in my barn). So it had been
in 50 degree temps for maybe 36 hours or so.

Go to start it last night - Ignition normal, "Wait" heater indicator on, etc. Once
that's done I turn the the start position everything went dead. A few flashes then
dead - The radio is now flashing on and off on it's own even without the key in it.
Had the battery load tested this AM after I charged it, fine. Put it back in, same
issue.

It seems like something primary in the circuit is not letting current through, even the
overhead light doesn't work. I think the radio is going on (default after losing power)
on some parisitic power then powers off when it uses it. If when the radio is flashing
I turn on the overhead light (light doesn't go on but flip the switch) the radio stops.
I can hear a faint click when I go from off to the ignition position like maybe it's a relay
that is defective.

I called a more local dealer and they will drop by to look but I'm worried it'll work by the
time they look at it (a few days maybe).

Any clues? The ground from the battery looks fine.

Makes me want to find a Cab tractor with no electronics and a
mechanical Hydro (Deere doesn't make any).

BTW, I went out to the other (unheated) barn where my trusty 2005 2305 (original battery) is
and hasn't been started in probably 3 months and it fired right up and I was able to do a
minimal but sloppy job of snow cleanup with the loader. (The 84" blower on the 4720 works
much better).

I have it on iPhone video also but I don't think I can upload videos here.

 

[CobyRupert]

"Once that's done I turn (to) the start position everything went dead." - Don't have a specific answer, but I'd suspect this is significant. Can't tell from your post, but does the battery go dead when you do this?
1st step is to see if voltage is getting to the starter when you turn the key to Start.

 

[orlo]

Battery does not go dead as far as I can tell - In fact this AM I know it didn't since I had charged the battery and just had it load tested. Last night voltage was good on the bat with a multi-meter. I suspect it's that 'burst' of current that is tripping a flakey relay. It's not just starting, EVERYTHING is dead, dash, etc. so power isn't even getting to the dash and other circuits pre-start. Worth noting is even the radio doesn't work on the accessory position turning counter clockwise.

 

[CobyRupert]

Worth noting is even the radio doesn't work on the accessory position turning counter clockwise.

Might want to check the key switch itself (voltage to it and leaving) or battery ground (again).

 

[grsthegreat]

i wonder about the key switch also. there are so many relays involved with the different things going out. There are relays for the cab lights, the dash lights, etc. i cans see them all failing. If its a new battery.....than the next step would be the key switch i would think... especially if all the grounds have been checked

 

[sunnyside360]

Had a similar problem with my 3720 cab tractor last winter. Wound up replacing the battery and all was good after that. Concluded the 6 year old battery was defective.

 

[orlo]

My original battery went after 2 years. This is only 2 years old and I went to buy a new one at the Auto-Parts store and they load tested it and stated it was fine. Could always have a strange issue though I suppose.

 

[JD5210]

I suggest you get a wiring diagram. You might ask and see if another member can provide you with one or maybe your JD dealer.

For now you might try removing all the fuses except the fuse(s) to start it. This will eliminate a number of components that maybe having a problem. See if it will start. If it does start. Start putting fuses in one by one.

If it does not start, while I do not know the wiring, I would think there should be nothing drawing voltage at this point. Take the negative battery lead off (at the battery or where it attaches to the frame), put a 12 test light between where you disconnected it. If the light goes on something is drawing voltage.

This is how I would start to figure out what the problem is.

 

[arlen4720]

It sounds like you have some bad connections or a bad battery.
My 4720 exhibits this behavior when the battery is near dead.
You need to break out the meter and see where you are losing the voltage.

 

[orlo]

Ok, it was the battery. I did a simple test - Hooked up a 10 amp battery charger (not enough to start but should run some lights), and the cab lights came on,
etc. Put a new battery in and it runs like a champ.

So the $700 meter (He told me how much it was) battery tester at the Auto Parts store is a POS .
Actually I suspect it was an intermittent problem with a cracked plate and maybe it passed on the meter.

Weird how this happened before an it 'cured' itself. I suspect it was a cracked plate that at certain temperature opened up
creating an open circuit. Strange that my battery charger reads this as 'charged'

Anyway, thanks for all the replies.

My only issue was (Nothing is ever easy) I got the same form factor battery (34) at Wal-Mart but the tabs on the bottom that
the mounts hold were too long so I had to file off the ends a bit - Was still so tight I had to enlarge the slots on the front
plate that holds the battery/hood latches. Oh Well. Nothing ever goes easy.