7775 Run / Service Switch??

[mrfixitpaul]

Trying to fix a customer's JD 7775, around 1997 model. He has broken the seat belt switch, removed and lost the parts...yay..he then jumped out the 2 wires to the seatbelt switch and had the machine running again, but pedals wouldn't unlock, so I got the call.
I have a lot of Bobcat experience, but none on JD skidsteer.
When I showed up, nothing works at all. Sit on the seat and nothing in the dash. Checked all fuses and they look fine.I flipped the Run/Service switch to Service, and machine starts, still locked pedals but I am not too concerned about that yet.
My question(s) are:
What is the purpose/function of the Run/Service switch?
Will I be creating a problem running the machine for extended period in Service mode?
Am I correct in thinking that when you sit in the seat the dash panel should come on, and machine should start? Then pedals should unlock when the seatbelt is latched?

Thanks for any help I may receive on this
Paul

 

[Mike10]

The service/run switch was used to start the engine without entering the loader for service purpose.
With the switch in the run position the lights on the instrument panel should come on when you sit in the seat. If he wired the seat belt wires together he may have caused a short and blew the 5 amp fuse in the engine fuse compartment. It should be the second from the bottom on the right fuse bank.
If the fuse is not blown then check if you have power to the seat switch(es). Then check if you have power coming out of the switch. You should also have power to the seat belt.
You could also disconnect the seat harness behind the seat and use an ohm meter to check for continuity between the pins of the connector. One wire is power in and the other two are power out from the seat switch and the other from the seat belt. With someone in the seat and the seat belt fastened I believe you should have continuity between all three pins.
If the two wires of the seat belt harness are connected together all the time you will not get the pedals to unlock. The system must see you sit in the seat first and then fasten the seat belt secondly before it will unlock the pedals.

 

[mrfixitpaul]

The service/run switch was used to start the engine without entering the loader for service purpose.
With the switch in the run position the lights on the instrument panel should come on when you sit in the seat. If he wired the seat belt wires together he may have caused a short and blew the 5 amp fuse in the engine fuse compartment. It should be the second from the bottom on the right fuse bank.
If the fuse is not blown then check if you have power to the seat switch(es). Then check if you have power coming out of the switch. You should also have power to the seat belt.
You could also disconnect the seat harness behind the seat and use an ohm meter to check for continuity between the pins of the connector. One wire is power in and the other two are power out from the seat switch and the other from the seat belt. With someone in the seat and the seat belt fastened I believe you should have continuity between all three pins.
If the two wires of the seat belt harness are connected together all the time you will not get the pedals to unlock. The system must see you sit in the seat first and then fasten the seat belt secondly before it will unlock the pedals.

Thanks Mike,
Sounds simple enough. I tested the fuses with a test light, but maybe I was in service mode at the time, as some fuses had no power to either side, but those that did were all good. The customer had jumped the wires for the seatbelt switch with a piece of wire and alligator clips, not insulated, so probably did compound the problem by blowing the fuse.
I figured there was some sort of sequence for the switches to be sure the operator was in the seat, thanks for confirming this. I know Bobcat uses sensors that change the resistance of the circuit and feed back to a computer, and has a time delay if the seat bar / seat sequence is not right, wasn't sure how JD did theirs.

Thanks again

Paul