JD 770 No Start/Power

[fishmen222]

Thank you all very much for your knowledge, but I fear this is a little different. I do not claim to be Mr. Goodwrench, but have been turning wrenches for three decades. I cannot load test on the tractor as I have no power. The battery has been load tested elsewhere and all is fine. Trading out batteries and cables did not help...same situation. How do I start diagnostics of where the open loop is? Removed all panels today and found no obvious damage. As stated before, all links and fuses intact. I am starting to lean towards the ignition switch, but cannot dismiss the starter. I have schematics, but where does the dash receive power from in the "on" position? Is it the secondary wire coming off the positive side of the starter? Thanks again folks for all your help!

 

[grsthegreat]

if the engine started with new battery, but then stalled out, i cant see how it would be the starter. maybe it is the ignition switch then.

Back in the good old days i used to know how to hot wire anything...those days are long gone.

 

[jenkinsph]

fishmen222,
jd 110 first suggested you measure the voltage while cranking, did you do this and what was the result? (NEVER ignore this poster as he always gives you good advise)
next, if the battery voltage remains high, continue with starter switch engaged then
measure the voltage from ground terminal on battery to battery cable terminal on starter solenoid, what is the result?
Next measure the voltage from the ground terminal on battery to the solenoid s terminal what is the result?
Next measure the voltage from the ground terminal on battery to the starter terminal on the solenoid, what is the result?

Without a method to the madness it is difficult to help you determine where the problem is this could all be done in less than a minute and would greatly help the troubleshooting process.

 

[fishmen222]

Sir, that is just it. I have not ignored anyone. I have had juice for all of three seconds and would have performed a load test if I actually believed it would have started at that moment. Unless I am missing something (and could well be), I cannot check load unless I am able to provide a load to test. I have power to nothing. Please correct me if wrong. Thanks again!

 

[Coyote machine]

Sir, that is just it. I have not ignored anyone. I have had juice for all of three seconds and would have performed a load test if I actually believed it would have started at that moment. Unless I am missing something (and could well be), I cannot check load unless I am able to provide a load to test. I have power to nothing. Please correct me if wrong. Thanks again!

You're not wrong about not being able to do a load test unless you can get her running , which is why I mentioned IF you can get it to crank. And yes, the smaller wire on the positive side of the starter solenoid will likely be your 'hot' wire, which should put 12+ volts to the solenoid when you turn the ignition switch to the crank position.
No one is questioning your knowledge- we're just doing our best to help point you in the right direction.
So now we know you have a good battery and cables. So put one side of you meter at the wire on the solenoid and one at the other end on the ignition switch and see if it reads any voltage when turning the key to crank.
Post back results. One step at a time. What is somewhat baffling is why you were able to get her started and then she immediately dies. We don't yet know if that symptom is electrical or fuel, do we?
Couple of other quick questions: what is the black relay you referenced in the first post? Does it have a number you can reference? Do you have a JD service manual or access to wiring diagrams?
Can you post a couple of pics of the starter/solenoid wires?

 

[jenkinsph]

Sir, that is just it. I have not ignored anyone. I have had juice for all of three seconds and would have performed a load test if I actually believed it would have started at that moment. Unless I am missing something (and could well be), I cannot check load unless I am able to provide a load to test. I have power to nothing. Please correct me if wrong. Thanks again!

So you are saying you have no battery voltage now? Change the battery if that is the case. Then proceed with the measurements. Who says you don't have a load? We haven't checked continuity through the starter circuit yet.

 

[jenkinsph]

fishman222
I think everyone would like to help you solve this starting problem, just understand that none of us are physically there. We would need you to run through a trouble shooting method so that we have a logical step by step process. Something else to keep in mind some of the Deere tractors had an additional relay to increase the voltage (or reduce the voltage drop) while cranking. Haven't determined if your tractor has this yet. Does your tractor have a 12v solenoid for fuel shut down? Loosing power to it will shut down the tractor when running. At any rate knowing the answers in a step by step procedure will make this easy.

 

[Coyote machine]

This may sound like a silly suggestion, but try removing the existing battery and jumping from your car or truck battery to the battery cables on the tractor (or else replace the existing battery with a known good battery). Don't just jump to the existing battery; take the existing battery out of the circuit.

I had a similar experience, and all of the symptoms pointed to something other than the battery. I even had a charger with 50 amp "Engine Start" connected to the old battery. When I removed the old battery and jumped from my truck battery it started. Another JD owner with a similar machine told me he had a similar experience.

When you figure it out, please post the results so future readers can benefit from your experience.

FWIW, jumping through a dead battery, even with the 50 amp start boost won't work if the battery has a dead cell. And though one can jump to just the cables of the dead vehicle/tractor it's better to replace a questionable/dead battery first, and then see if it will start.

This situation looks like a fuel shutoff may be kicking in right after the tractor starts, but there are some issues that need to be resolved before that can be determined for certain. One of them is whether the ignition/start circuits are able to do their job. We are waiting for more info from the OP at the moment.

 

[Henri88]

It's sound more like an electrical problem. He say's that all power at the instrument panel goes out. This is why I mention a possible bad ignition switch. Good luck Fishmen and keep us up dated. :thumbsup:

 

[jenkinsph]

fishman222,
Did you get this fixed? You can look at the wiring below and research Deere parts for more information.