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Discussion Starter #1
Hi guys,

New to posting but have used this board many times to fix issues with my 1999 JD 455.

I'm currently diagnosing an electrical issues that seems to be related to my key switch and board, but could be something else as well.

Tractor ran normal then seemingly out of nowhere when trying to start, dash lights come on, go off, then dead. Turn key off, then back on, nothing, no dash lights, nothing.

Replaced key switch and board with correct module for my later model year, problem solved. After about 4 cuts, same thing, when trying to start, dash lights on as normal, solenoid fires as normal, then at some point before firing up it dies.

Replaced key switch and board again, fires right up. About 4 cuts later...yep, you guessed it, died again...and that's where I stand today.

Now, I did some more digging using my tech manual and found that my battery is good (12.8V) and good power all the way through the key switch board (control/fuse module) to terminals 2 and 6 without the next wiring harness attached (i.e., fuses good, key switch good). But when I connect the power connector harness to the control/fuse module (X1) the voltage across the system drops way down to about 3.8-4.0V then slowly climbs to about 6V after minutes of sitting there. My dash lights glow dim and a bit brighter but obviously not enough voltage to do start the tractor.

Anyway, could this be a short in the wires after the key switch board? A blown board (again?) or what?

Any help is much appreciated!

Thanks,
Brian
 

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Discussion Starter #3
Connections at battery and starter are good. Would a bad ground cause the drop in voltage? Is there a way to check for a bad ground? Thanks!!
 

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Pay close attention to the cable ends, not just the connections. Mine looked fine but were corroded inside the cables. It acted exactly the same. Also follow the wires from the starter to the board and dash and make sure all connections are good and not corroded.
 

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Thanks! I'll give the wires and connectors a good look over and hopefully find the smoking gun.

I'm checking voltage with my Fluke Multimeter set on DC with the JD 455 key switch on and the park brake engaged. My red cable goes to the test point and the black on the grounding point at the motor mount. I get a solid read of 12.8V at the battery, the starter, the key switch power connector, and terminals 2 and 6 of the control/fuse module of the key switch board. Not until I connect the power connector wire bunch to the key switch board (the wires going to the seat switch, brake switch, rectifier/regulator, dash, and then on from there) do I get the lower (~4.3V) reading.

Thinking that I need to isolate each wire coming out of that power connector wire bunch to see which causes the voltage to drop when connected then repair from there? Not sure yet how I'll do that but I'll figure something out.

Also, I can't seem to figure out why changing the key switch board seems to solve the problem for the short term?

Either way, thank you to everyone for your continued comments, I enjoy learning from your experiences.
 

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With everything connected when you are getting your ~4.3v reading go back and check battery voltage with both leads on the battery posts. If you still have ~12.8v move the red lead to the starter, check voltage there, then to the X1 connector to the key switch and check voltage there. If at any of those points your voltage drops from 12.8 to 4.3 you will know where your problem is at.

There is a fusible link between the post on the starter and the X1 connector that has a splice to connect the Red/Black that feeds the C terminal on the X13 connector on the A1 Diesel Module. You could also check voltage at that connector.

I assume that your tractor is a 1999 model or newer (SN 70001-). Is this correct?
 

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Thanks! I'll give the wires and connectors a good look over and hopefully find the smoking gun.

I'm checking voltage with my Fluke Multimeter set on DC with the JD 455 key switch on and the park brake engaged. My red cable goes to the test point and the black on the grounding point at the motor mount. I get a solid read of 12.8V at the battery, the starter, the key switch power connector, and terminals 2 and 6 of the control/fuse module of the key switch board. Not until I connect the power connector wire bunch to the key switch board (the wires going to the seat switch, brake switch, rectifier/regulator, dash, and then on from there) do I get the lower (~4.3V) reading.

Thinking that I need to isolate each wire coming out of that power connector wire bunch to see which causes the voltage to drop when connected then repair from there? Not sure yet how I'll do that but I'll figure something out.

Also, I can't seem to figure out why changing the key switch board seems to solve the problem for the short term?

Either way, thank you to everyone for your continued comments, I enjoy learning from your experiences.
OK, when you connect the "wire bunch" to the key switch board, do you still have 12.8 VDC at the battery and at the starter?
 

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Discussion Starter #9
Good stuff. I know that once I get the lower voltage reading, I also get the same (lower) voltage read at the starter (I did check that) but I did not check it at the battery terminals. I will check that as well as your other suggestions. Unfortunately, the tractor is at a location other than my house so my time to diagnose and fix things is limited. I'll probably be out there again tomorrow but at least I have a plan of attack thanks to the suggestions here!

Yes, it is a newer model 455 (and I really do love the machine!).
 

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Good stuff. I know that once I get the lower voltage reading, I also get the same (lower) voltage read at the starter (I did check that) but I did not check it at the battery terminals. I will check that as well as your other suggestions. Unfortunately, the tractor is at a location other than my house so my time to diagnose and fix things is limited. I'll probably be out there again tomorrow but at least I have a plan of attack thanks to the suggestions here!

Yes, it is a newer model 455 (and I really do love the machine!).
If you are seeing the lower voltage at the starter, it is most likely you will also see the lower voltage at the battery.

If you also see the lower voltage at the battery, then you problem is either the battery terminal connections are corroded or the battery is bad.

It is very possible, and highly likely, for a battery to check good when not loaded and when a load is applied, the voltage will dive.

Connect your voltmeter to the battery terminals, check the voltage; then turn on the lights and check the voltage.
 

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If you are seeing the lower voltage at the starter, it is most likely you will also see the lower voltage at the battery.

If you also see the lower voltage at the battery, then you problem is either the battery terminal connections are corroded or the battery is bad.

It is very possible, and highly likely, for a battery to check good when not loaded and when a load is applied, the voltage will dive.

Connect your voltmeter to the battery terminals, check the voltage; then turn on the lights and check the voltage.
I agree. I am thinking he needs to "Load Check/Test" the battery. It sounds like a bad battery that can't maintain the load.

If you do not have a way to load test the battery try putting a battery charger on and see if you get the voltage drop when connecting the X1 connector.
 

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Before you start chasing electrical gremlins you need to verify that your battery is good. (remember verify, that means load test, not just a voltage test) If the battery cables have never been replaced, I'd replace them to further verify their condition. The ground cable requires a bit of effort to change. It's on the injection pump side under the motor mount. You'll need to take the mounting bolt out and use a prybar to lift the engine to get to it. The positive is easier to see and access. You don't need john deere cables. I bought 2 2 foot hoop cables from AutoZone and used bolt on to post converter ends that are imo much better than one for attachment and corrosion resistance. Electricity is a strange animal and can do some very strange things when the supply isn't correct or there are connective issues.

Here's something a bit unrelated but in the same vein. My house was dropping one electrical leg and I was losing current flow to half my house which destroyed a microwave, washing machine, all my t8 garage and shop ballasts, 2 tv's etc and the house side wasn't the issue. After 3 calls to the power company, and 3 different techs, more ballasts, and another microwave, the 3rd finally began replacing the overhead drop from the transformer to the meter and found burned lugs at the meter socket. 1 bad connection caused all that grief.

Voltage tests are useful but are limited, in scope. As others have noted, you can have a battery read 12 volts until its loaded. The same applies to the connections. My guess is you will be pleasantly surprised if you do as suggested.
 

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One quick thing to check. Unplug your fuel shutoff solenoid and see if that makes a difference. You will have to manually move to get it to start. A bad solenoid will pull battery down or blow a fuse. Happened to mine.
 

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Thanks again to everyone for the help. It turned out that I had 12.8V at the terminals after the voltage drop so it turned out to be an issue with the battery to clamp connection. The bolt that secured the clamp had a bunch of orange/white colored dust on it so I cleaned up the inside of the clamp, the terminal heads themselves and replaced the bolt and the JD455 fired up like a champ. Funny thing is that the inside of the clamp itself looked great, no corrosion to the naked eye. I sanded it anyway just to be sure but just goes to show that corrosion could be easy to miss!

Also, I'm still not sure why replacing the key switch board the last time "fixed" the problem temporarily but I feel much better with this solution. Thanks again!
 

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You may have a spare key board now
 

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Thanks again to everyone for the help. It turned out that I had 12.8V at the terminals after the voltage drop so it turned out to be an issue with the battery to clamp connection. The bolt that secured the clamp had a bunch of orange/white colored dust on it so I cleaned up the inside of the clamp, the terminal heads themselves and replaced the bolt and the JD455 fired up like a champ. Funny thing is that the inside of the clamp itself looked great, no corrosion to the naked eye. I sanded it anyway just to be sure but just goes to show that corrosion could be easy to miss!

Also, I'm still not sure why replacing the key switch board the last time "fixed" the problem temporarily but I feel much better with this solution. Thanks again!
Its obviously your tractor and your decision but that green corrosion can be inside the vinyl insulation where you can't see it. Again, from experience, spend the minimal $ to replace the cables. Glad to help. :hi:
 

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Thanks again to everyone for the help. It turned out that I had 12.8V at the terminals after the voltage drop so it turned out to be an issue with the battery to clamp connection. The bolt that secured the clamp had a bunch of orange/white colored dust on it so I cleaned up the inside of the clamp, the terminal heads themselves and replaced the bolt and the JD455 fired up like a champ. Funny thing is that the inside of the clamp itself looked great, no corrosion to the naked eye. I sanded it anyway just to be sure but just goes to show that corrosion could be easy to miss!

Also, I'm still not sure why replacing the key switch board the last time "fixed" the problem temporarily but I feel much better with this solution. Thanks again!
Having a battery load tester which also checks alternator output is very handy to have. It helps to narrow down a culprit quickly. I have this one and really like it.

Electronic Specialties Battery Tester Load, 6/12V, 1000 CCA 700 | Zoro.com

It helps to eliminate the battery while under load as simply testing the battery voltage is often misleading. Many of the batteries I have replaced in all of the vehicles over the years usually shows around 12 volts on the volt meter. But the moment you put the load on the battery, it really separates the good and bad very quickly. It's also very handy to know the alternator output at the battery as that helps to eliminate many possible culprits.

I have had a few electrical issues over the years with my 455 and in every case, it was a simple repair and never something buried in the wiring. I will say that when something has been repaired, especially by others, you have to carefully check the plugs on the harnesses which they might have disconnected as I have found on more than one occasion where someone grabbing the wires on each side of the plug ended up pulling individual wires in the harness out of the plug on one or both sides.

Once you do open the plug to check it, the problem usually is very obvious as one or more of the wires will be pulled back to a fraction of the other pins in the connector. I have also seen where when someone tried to plug the two halves together when not aligned correctly, they bent one or more of the pins in the plug. This is impossible to find without disconnecting the plugs and checking the pins on both sides visually. It's maddening to search and search for the problem only to find that someone else's improper handling of the plug and wires caused the problem.

When my new tractor was delivered, the rear wiper for the cab and the revolving light had not yet come in. I took delivery of the tractor and told the dealer I would install the wiper and the light on my own. I picked up the parts and installed them. The light worked perfectly, however I could not get the rear wiper to work.

I fiddled around with it and tested the wiper motor with another power source and it worked. When I looked at the harness on the new wiper motor and the harness in the cab, the wires by color code inside the plug were in different locations on the plug. I took a picture of both before changing the wire locations and I changed the wiring on the wiper motor plug first, by pulling the pins out and reinserting them to match the harness in the roof of the cab. Problem solved. Someone at the wiper motor maker wired the plug incorrectly. Brand new wiper motor and wired incorrectly from the manufacturer. It always pays to check the details. :dunno:
 
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