Case 750K won't release parking

[Slim Tech]

Working on a
Case 750K
s/n; JJG0365210

Machine stopped and gave transmission fault light, no can, and parking brake light all came on while operating. Removed the dash and found multiple broken wires, rubbed wires, and corroded connections. Removed the panel and repaired all wires. Reinstalled and everything is acting properly now, switches all work, dash shows F-N-R, etc. However the parking brake won't release still. You can only start it with at least one of the levers up, the lights on the lever sensors are both acting properly (orange and green when up, green when down). All fuses are good, relays are good. Not sure what to check next? currently looking to see if there is a seat sensor as well, but not sure on this model.
TIA

 

[guisep3]

Replace ALL fuses. I have a dc85 new Holland which is basically the exact same machine. I had your same issue.
I spent thousands on mechanics all to figure out the 1 amp fuse was my problem. Don't test the fuses, change them.
No can means the 3 controllers aren't communicating properly.

On another note, could you please help me? My employee lifted the cab and didn't disconnect the throttle rod. Out ripped the top half of my injector pump off. Had pump rebuilt, but now my rod is bent and I'm not sure if the linkage arm that the quick disconnect hooks on to is bent?
Could you send me a picture of the throttle rod where it bottle on to your injector pump and connects to the lever with the quick disconnect?
My lever is bent 20deg inward right where the ball is bolted on.

Thx so much. Good luck

 

[Jdtech99]

Currently working on a 650k case. Park brake will not release. All fuses and relays seems to be ok. With both levers down the park symbol is still illuminated on the dash. Any ideas?

 

[Slim Tech]

Make sure the wiring going to each sensor at the base of the levers is good and that the lights in the sensors are illuminated.

My problem ended up being a rats built a nest behind the instrument panel, had to remove the panel and harness to make repairs to the wiring.

Also replaced every fuse, corrosion was hindering some connections and I replaced 1 bad relay as well.

Hope that helps

 

[Jdtech99]

The park break sensors seem to be all sound. The machine is not showing any codes. The park brake levers are reading because with both up engine starts. With left lever down engine starts. I can then put just the right lever down and engine will start. I can put both levers down and get a no start. So I believe everything is right there. Does anybody have a wire diagram for the park brake circuit?

 

[leojmartin]

I’m working on a 750K with the same problem. Both brakes locked up. I found That a rat had eaten the wires to the parking break solenoid. I made repairs to that wiring. It’s located on the left side of the machine accessible through The bat wing door. Mounted to the fuel tank.
With that done my right track is free but the left trace is still locked. I’m worried I have internal brake problems. Any ideas before I dig deeper.

 

[leojmartin]

The park break sensors seem to be all sound. The machine is not showing any codes. The park brake levers are reading because with both up engine starts. With left lever down engine starts. I can then put just the right lever down and engine will start. I can put both levers down and get a no start. So I believe everything is right there. Does anybody have a wire diagram for the park brake circuit?

 

[leojmartin]

I’m working on a 750K with the same problem. Both brakes locked up. I found That a rat had eaten the wires to the parking break solenoid. I made repairs to that wiring. It’s located on the left side of the machine accessible through The bat wing door.Mounted to the fuel tank.
With that done my right track is free but theleft trace is still locked. I’m worried I haveinternal brake problems. Any ideas before I dig deeper.

 

[leojmartin]

I have a drawing. headed your way. It's a bit hard to read without the full manual but this may help.

 

[leojmartin]

I have a drawing. headed your way. It's a bit hard to read without the full manual but this may help.

Here is the full electrical section from the manual.

 

[Coy Lancaster]

Currently working on a 650k case. Park brake will not release. All fuses and relays seems to be ok. With both levers down the park symbol is still illuminated on the dash. Any ideas?

Your park brake solenoid is probably bad. Its located right in front of the fuel tank on left side of machine.