Terex PT50, Aux Hydraulics not engaging.

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New member
Sep 4, 2023
Hi everyone.
I've been reading through the posts to try and find this specific issue and haven't been able to solve it.

We have a Terex PT50 that runs great and attachments (that don't require the aux hydraulics) all function well. Buckets, forks, etc.

When I connect anything that needs the Aux Hyd it doesn't engage. Here's what I've checked:

- The hose quick connects connect easily.
- the overhead switch (pic) works as-in if the switch is ON the machine won't start. So, it knows when the switch is engaged... The switch on the right for the quick attach works fine to lock/unlock attachments.
- the fuses are good, except for one for "micro sw" (Pic) I need to find this short. Is this mirco SW fuse a part of the problem?
- checked the relays ohms and they are OK (78ohms +/-).
- The right joystick works to run the bucket and lift etc. The horn button works. The other thumb button (wide one) is supposed to be the intermittent Aux Hydraulic button. When I press this, nothing happens.

Next thing to check is the "Pilot generation block".

Does anyone have any suggestions on other troubleshooting I can try?

Thanks and much appreciated.



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New member
Mar 26, 2024
Did you figure this out? My PT110f is doing the same thing. Continuous hydraulics work with my brush hog but the thumb switch does nothing for my tree puller. I purchased a new joystick and it did not fix the issue. Relays/fuses are good. Does the thumb switch operate a different solenoid than the continuous?