JD 4300 puzzle

[Dentbla]

New member, first post. I have a JD 4300 HST. When I step on forward or reverse pedal, it dies. When I engage rear PTO. it dies. I have bypassed the seat safety switch, I have replaced the switch that is activated by the forward/reverse pedals, and the two neutral safety switches. Fluid levels all good. Now for the fun part...if I pull up on the hand brake, the PTO will engage. If I bypass the forward/reverse pedal switch, the tractor will drive. Cleaned the fuse box area and pulled all fuses/relays out and cleaned terminals. I also switched the relays around as they are all the same, no luck. Front loader works fine and three point hitch raises and lowers.
I am lost for ideas...please help me!
Thanks in advance.

 

[jthibodeau89]

Sounds like the safety circuit is cutting the power to the fuel solenoid. Perhaps a damaged wire? Do you have a manual with the electrical diagrams?

 

[TractorGuy]

My guess is the wiring to the seat switch is damaged making it open even though you bypassed at the switch.

 

[Dentbla]

Sounds like the safety circuit is cutting the power to the fuel solenoid. Perhaps a damaged wire? Do you have a manual with the electrical diagrams?

Thanks 89, I traced the wiring harness looking for anything questionable, but I guess a damaged wire would be like finding a needle in a haystack. I just have the schematics available on the JD web site. Do you know if the switch on the lever brake is part of the safety circuit?

 

[Dentbla]

My guess is the wiring to the seat switch is damaged making it open even though you bypassed at the switch.

Thanks TG, is there a way with a meter to confirm a damaged wire?

 

[joecdeere]

Check your private messages

 

[jthibodeau89]

Thanks 89, I traced the wiring harness looking for anything questionable, but I guess a damaged wire would be like finding a needle in a haystack. I just have the schematics available on the JD web site. Do you know if the switch on the lever brake is part of the safety circuit?

Ill check my manual.

 

[jthibodeau89]

Yes, the parking brake switch is part of the safety circuit. "If trans in neutral, pto disengaged, , then set park brake, operator can leave seat and then re-engage pto." So park brake seitch will allow the ptp to be engaged without operator in seat.

From the manual:

"Engine must stop is pto engaged and operatpr leaves seat"

"Engine must stop if transmission is engaged and operator leaves seat"

It sounds like your sear switch wiring may be the culprit

 

[dodge man]

I had a car I restored years ago with a bad wire for a power window. I gave up trying to find the break and just ran new wires. Still a pain but it did fix it.

 

[Dentbla]

Thanks everyone for sound advice. I got a schematic so will be checking everything this weekend.

 

[jthibodeau89]

First check continuity or 12v on seat switch harness red wire with key in run position. Then check continuity between seat switch white wire and diode block terminal 4. One of those 2 is broken. Or your jumper was bad.

 

[Dentbla]

Thanks again 89, I get 12v+ to my seat switch harness. Continuity ok between seat switch white wire and diode block terminal 4...still searching.

 

[Dentbla]

Also, jumper on seat switch checks out.

 

[jthibodeau89]

So with jumper in you have 12v at diode block terminal 4?

 

[Dentbla]

Update, **** you 89, you were correct. When I was lifting the seat sensor up to test, it was giving me 12+volts. I rechecked everything today, hooked another wire to the seat sensor, let it drop back to normal position, and went to engine for ground, and voltage was crap. The wire to terminal connections on seat sensor were severely corroded, cut them off, cleaned wires, and put on a wire nut. Working as it should now. Will test drive and put things back together tomorrow. Thank you, thank you , thank you!!!

 

[Dentbla]

**** is dam*

 

[jthibodeau89]

Glad you found it. But i don't onderstand 1 thing. You said seat contacts are bad, but that you had a seat jumper installed. If seat jumper is installed, the seat seitch contacts do not matter.

The explanation below was written before i read your response. It is another possible issue.

If you have 12v at diode block terminal 4 with key on, and jumper installed, next check K4 engine run relay terminal 86. It should have 12v with pto on. K4 terminal 86 is the far end of diode block terminal 5 which should also have 12v with both the seat occupied and pto (or) trans on, and with seat empty but pto&trans off. You need to check both conditions. The pto off / trans neutral also feeds V1 terminal 5 so that engine will continue to run when out of the seat with pto off/ trans neutral.

Have you confirmed v1 diode block is ok? The K4 engine run relay (V1 Diode terminal 5) is fed by 2 circuits; the seat switch (V1 terminal 4), and the PTO off / trans neutral (V1 terminal 6). It sounds like whenever you interupt the terminal 6 feed, your engine run relay is cut. This will occur with a bad V1 diode block ot bad seat safety circuit.

 

[Dentbla]

Sorry, my jumper wire had .250 male spades attached to it. The connector that attached to the switch, or the jumper, was severely corroded. I would pick it up and test for 12v and it was okay. With your persistence that it was probably the problem, I did further checking and found that when I wasn't holding it the voltage would jump all over. That is when I removed the connector and used a wire nut to attach the two wires. The wires themselves were black and I had to clean them. I will print and keep your new info just in case, Thanks.

 

[jthibodeau89]

Ahhh. Wire terminals to plug on harness was bad. Got it. That was root cause. Easy fox pnce you found it. I had the pto switch on my 4300 go out. Had to jumper it to get back to the shop. New switch was about $50.

I'm making new inner tie rod ends now. Reworking a car part that cost $19 ea instead of the $100 ea that JD wants.