Kubota M7040 electrical issue

Knifemaker · Jul 10, 2013

I am new to this forum and I am not a mechanic but here is my problem. I have a Kubota M7040 Diesel 4WD tractor with cab. After some use (and maybe abuse) by a farm employee, the fan for the air conditioner/heater stopped working. When the weather in Alabama got hot, he complained and I was made aware of a problem. Before I could address the fan problem, other electrical components began to fail (hazard lights, work lights, etc.) but yet the tractor started right up when I went to drive it from the remote field to my workshop at home. My NEW farm helper began searching for a fix. He has checked every fuse (that we know of), every relay switch, every wiring harness, literally everything he can think of as a problem. As a result, he now has the fan working. He has every light, flasher, etc. working. BUT we are unable to start the tractor from the key ignition. He cranked it once this morning from the key ignition but has not been able to crank it again. He thinks there is a short that may have blown a fuse/relay but which one and where? We purchased a new relay switch related to the starter but that has not solved our problem. We can start the tractor with a straight connection but just not with the key. We know the ignition is good but we don't have power at all points of the wire harness that comes from the tractor wiring to the harness that connects to the ignition. The Owners' Manual is pathetic at providing information about relays. We found a whole panel that was not even mentioned in the manual. I have ordered a Service Manual (to the tune of $119.00 + sh) which I should have tomorrow but can anyone shed any light for the time being as to where we may have missed a relay or fuse that services only the starter?

rbargeron · Jul 10, 2013

The older Kubotas have a fusible link very near the starter - a loop of red wire in a white plug connector. Some models have a large fuse in the plug. It's purpose is to protect the system against reversed voltage (like jumper cables or battery connected wrong). No idea if this is present on an M7040.

KennyV · Jul 10, 2013

You will have to learn a few 'diesel' engine terms... When you start using a Work Shop Manual, they are going to refer to components by their actual name... You do not have an ignition.
If you are referring to the key switch, and specifically the starter circuit, there are several 'safety interlocks' in that starter circuit path.
If you are getting power to the key switch & main fuse block the large fuse or fusible link is going to be good.
If your problem is the engine will turn over using the starter, but will Not start, the problem is in the fuel shut Off system.
If the problem is the Starter will Not engage at all... the problem will be in the interlocks Or or associated wiring.

Knifemaker · Jul 10, 2013

Thanks. I looked but didn't see anything like this on mine. It is a 2008 model. We bypassed the above mentioned wiring harness and connected the wires direct to each other and now we have power through all connections. Still won't crank with key. Hopefully, the service manual arrives tomorrow and will provide the answer. We may go ahead and pull the seat out again just to make sure we haven't damaged the connection to the safety switch that keeps the tractor from running under certain circumstances when the sensor fails to detect an operator.

Knifemaker · Jul 10, 2013

Thanks KennyV. I just read your post. Based on what you say, the problem must be in one of the safety interlocks and/or wiring. I will try to let you both know if and how we resolve the problem without calling in a Kubota service man.

wmonroe · Jul 10, 2013

I would try and jumper out the seat switch to see if that is the issue.

Tx Jim · Jul 11, 2013

There should be 3 safety switches on the start circuit.
shuttle shift switch,pto switch & seat switch which only comes into play when pto switch is activated. I would look for no continuity on shuttle &/or pto switch when each are in neutral.

Berryking · Jul 4, 2014

Knifemaker said:
I am new to this forum and I am not a mechanic but here is my problem. I have a Kubota M7040 Diesel 4WD tractor with cab. After some use (and maybe abuse) by a farm employee, the fan for the air conditioner/heater stopped working. When the weather in Alabama got hot, he complained and I was made aware of a problem. Before I could address the fan problem, other electrical components began to fail (hazard lights, work lights, etc.) but yet the tractor started right up when I went to drive it from the remote field to my workshop at home. My NEW farm helper began searching for a fix. He has checked every fuse (that we know of), every relay switch, every wiring harness, literally everything he can think of as a problem. As a result, he now has the fan working. He has every light, flasher, etc. working. BUT we are unable to start the tractor from the key ignition. He cranked it once this morning from the key ignition but has not been able to crank it again. He thinks there is a short that may have blown a fuse/relay but which one and where? We purchased a new relay switch related to the starter but that has not solved our problem. We can start the tractor with a straight connection but just not with the key. We know the ignition is good but we don't have power at all points of the wire harness that comes from the tractor wiring to the harness that connects to the ignition. The Owners' Manual is pathetic at providing information about relays. We found a whole panel that was not even mentioned in the manual. I have ordered a Service Manual (to the tune of $119.00 + sh) which I should have tomorrow but can anyone shed any light for the time being as to where we may have missed a relay or fuse that services only the starter?

So want was the problem with your tractor?