M7040 no start but weak attempt

[gwdixon]

I did a search but didn't find the problem I'm having with a M7040HD-1.

When turning on the ignition, the dash warning lights are fine but the center rectangle (with the hours etc.) is very dim and unreadable.

When the key is turned to the start position the starter tries to turn over but won't. Trying again and again just results in eventually the starter not responding. Dead battery - right. Nope. One of those ion jump starters was tried and it acted exactly the same as without it. The jump starter didn't show a drain.

But a brand new charged battery was put in anyway since the old one was still under warranty. Nope. Exactly the same response. Just like a very weak battery might do.

Plus, the tractor's front and rear lights do not turn on with the ignition switch in the run position.

I've ruled out a safety switch problem since the tractor tries to start. Next will be to pull the starter and test it but it doesn't seem like that will be the source of the problem since other electrical problems unrelated to the starter are present. Fuses are likely not it since some flickers of light on the dash and power at the starter seem to be there.

This just happened today so I've not gone down a complex diagnostic path yet. What I'm seeking from the folk on TBN is some direction to start looking rather than replacing parts until something works.

 

[RoyKing]

Starter solenoid contacts or starter windings. First thing check all connections for tight and clean, I would remove wire brush. then if can expose solenoid contacts clean them. Then remove starter test on bench. Then rebuilt starter, check auto stores Kubota uses common starters.

 

[gwdixon]

Starter solenoid contacts or starter windings. First thing check all connections for tight and clean, I would remove wire brush. then if can expose solenoid contacts clean them. Then remove starter test on bench. Then rebuilt starter, check auto stores Kubota uses common starters.

Thanks. I'll check those suggestions out. I certainly want to make sure it is the starter before dropping big bucks.

Kubota M7040 starters are made by Mitsubishi and run $450+ from Kubota dealers. Ebay has new (they claim) off-brand for around $120.

 

[RjCorazza]

With the work lights not coming on in run position, it sure sounds to me like a bad connection. Check all battery connections (remove, clean, tighten) including grounds.

 

[Tx Jim]

My guess is corroded/loose negative battery cable connection especially at tractor frame or bad negative cable

 

[SDT]

I did a search but didn't find the problem I'm having with a M7040HD-1.

When turning on the ignition, the dash warning lights are fine but the center rectangle (with the hours etc.) is very dim and unreadable.

When the key is turned to the start position the starter tries to turn over but won't. Trying again and again just results in eventually the starter not responding. Dead battery - right. Nope. One of those ion jump starters was tried and it acted exactly the same as without it. The jump starter didn't show a drain.

But a brand new charged battery was put in anyway since the old one was still under warranty. Nope. Exactly the same response. Just like a very weak battery might do.

Plus, the tractor's front and rear lights do not turn on with the ignition switch in the run position.

I've ruled out a safety switch problem since the tractor tries to start. Next will be to pull the starter and test it but it doesn't seem like that will be the source of the problem since other electrical problems unrelated to the starter are present. Fuses are likely not it since some flickers of light on the dash and power at the starter seem to be there.

This just happened today so I've not gone down a complex diagnostic path yet. What I'm seeking from the folk on TBN is some direction to start looking rather than replacing parts until something works.

Sounds like battery cables or connections.

Be advised that battery cables can be badly corroded inside of the insulation resulting in loss of current carrying capacity with little or no visible evidence.

SDT

 

[gwdixon]

All great ideas - thanks.

Hope the cure is that simple. Testing the cables with a voltmeter / continuity tester is first, for sure, but it doesn't indicate amps which are required for starting.

I think I'll bypass the battery cables with a jumper cable and see what's up with that.

My old L3650 had a battery negative ground problem that cleared up instantly with a new cable and cleaning the grounding bolt and area. Should have thought of it already. But the cables look so good! Ah...old age is getting to my brain cells.

 

[sixdogs]

My guess is corroded/loose negative battery cable connection especially at tractor frame or bad negative cable

Sounds like a bad ground.

 

[gwdixon]

UPDATE:

The problem doesn't seem to be a ground issue. Continuity to ground is fine and a jumper cable from the negative battery terminal to an engine bolt doesn't bring the electricity to life. Battery is fully charged.

The starter test in the WSM for 12V power to the starter shows 12V at the solenoid. So it is not a positive cable problem.

Now the dash lights don't work at all BUT the gas gauge works just fine. Also, the hazard light switch will turn on and the switch will flash but dim on the dash. The tractor's lights still don't react to the hazard switch or headlight/turn signal.

The low electrical output has me stumped. A fuse would kill it all rather than allow a low output. A relay is the same - either it works or it doesn't in my experience.

I don't think it is the ignition switch because of the odd behavior of the other components. The hazard light doesn't rely on the ignition switch but the gas gauge does rely on the switch and reacts to the switch being turned on/off.

What component would just allow a trickle of electricity enough to raise one's hopes but not enough to engage the starter or operate the lights? There is some blockage somewhere it seems.

 

[davedj1]

Just because the battery shows a full charge doesn't mean it's so. I just went through this the other day, I put my charger on the battery, waited about 2 hrs and nothing, still showed fully charged. Couldn't get a load test at the dealer, their machine said re charge and tray again...lol
I installed a new battery and both new cables along with cleaning up (wire wheel) all connection points, she starts like a new tractor now. Good luck.
ETA: what is the voltage at the battery? Mine only showed 11.8 volts.