Deere 955 Won't start - good battery and starter

[Enimo]

I have a 955 that was running perfectly two days ago. My brother-in-law was using it at his place and could not park it inside that evening so he left it outside. He lifted the seat forward and it poured rain that night. Went back today to use it and it will not turn over. I met him there and this is what I know. The battery is good as I took a brand new one to make sure. Good continuity from battery ground to frame and from battery to starter. When you turn the key there is no click nothing. You can turn the lights on and when you turn the key they go out. Sounds like a short to me or possibly the starter. I tapped the starter to see if it may be hung up, it did nothing. I removed the starter completely and turned the key and it did exactly the same thing. All the gauges work and the lights go out when I turn the key. So, I know it isn't the battery or the starter. My guess is the ignition switch or a safety switch somewhere. Any ideas other than jumping each safety switch to see if one is bad (corroded, loose, etc.)? Many thanks for any input.

 

[sweettractors]

Sounds like a bad ground connection on the battery or starter. Possibly bad safety switch under seat that got wet? Ken Sweet

 

[Enimo]

In reading and reading and reading on this forum it seems that the only safety switch that would keep it from starting is the neutral switch, is this correct? Sounds like the others only work when the engine is running - get off while PTO is engaged and the PTO stops, etc. I think I will check neutral switch first. Thanks

 

[joecdeere]

those are famous for bad grounds where bolts to frame, pull cable and clean connection to frame, not just tighten

 

[Richard001]

Enimo said: So, I know it isn't the battery or the starter.

I'm a little confused about how you know it's not a starter problem.

Try jumping the battery positive terminal directly to the starter terminal. If the starter spins, then you know that is is not a starter problem.

Richard

 

[Kish318420]

After cleaning, I would use 3 external star washers also. 1st star washer goes between head bolt and frame. 2nd start washer goes between frame and cable end. 3rd star washer goes on top of cable and nut. Also remember to use dielectric grease to protect from corrosion on the assemble as you put it together.

 

[bruceatlam]

If you left the PTO on, those symptoms will occur. A bad seat switch can cause those symptoms as well as a bad brake switch.

 

[k0ua]

No shorts - shorts burn up things. As mentioned, check your ground connection. Otherwise, I would say you have a bad cable. How did you check the continuity of the cables - multimeter on Ohms scale? That doesn't do anything toward testing a cable under a load.

1) Take your meter and put it on a scale that would read 12 volts DC. Put one lead on a good ground spot. Put the other lead on the battery negative terminal, not the cable connector. Try to start the tractor and then read the voltage when trying to start it. If it reads 0-1 volt, cable is OK.

2) Do the same with the positive cable - one lead on the starter connection and one lead on the positive battery post. Try the start routine again and read the voltage. If it reads 0-1 volt, cable OK. If either test reads around battery voltage, you located the bad cable.

It is very difficult for people with no knowledge of Ohm's law to understand the concept of a high resistance connection. And as for reading the voltage drop across a piece of wire (like a battery cable) you might as well have posted in Greek. Most people think a wire is a wire is a wire. You are right of course as the lights going out when the key is turned is a very telling clue. To most people there must be a "short". That is what causes all electronic problems isn't it? You know, a "short". I wish we as a society taught useful things in school. Like Ohm's law for instance. Very useful in real life. Some of the other things we teach, um... not so much.

 

[Richard001]

After cleaning, I would use 3 external star washers also. 1st star washer goes between head bolt and frame. 2nd start washer goes between frame and cable end. 3rd star washer goes on top of cable and nut. Also remember to use dielectric grease to protect from corrosion on the assemble as you put it together.

While putting a star washer between the battery cable and the frame ground appears to be a good idea, it is not.

Star washers a notoriously poor conductors of electricity. At the company that I worked for, some of the units were melting the insulation off of a heavy gauge wire, a #6 I believe it was. This was the ground connection for some 12V DC fans. After some investigation, I discovered that the Stainless steel star washer was causing the poor contact to the frame member.

I would not recommend it.

Richard

 

[Enimo]

I'm a little confused about how you know it's not a starter problem.

Try jumping the battery positive terminal directly to the starter terminal. If the starter spins, then you know that is is not a starter problem.

Richard

Well, Richard, you are right now that I think of it. I guess I am not 100% positive but when I tried to jump it from the battery I got a big spark but nothing else because I took it off quickly ..kinda didn't want to do that again. So I took the starter off and disconnected it completely and it did the exact same thing when I turned the key, lights went off. I am not sure why it sparked so much when going from the battery to the starter. Tomorrow I will try to jump it again and maybe that will tell me more. Thanks for the help!