Gehl RS5-34 brakes not releasing isnt electrical issue

NOT ABS lamp , right?
the parking brake is adjusted first pre the service manual then
the switch must be adjusted to for closure brake released;
i use volt meter that switch after install and make sure it works
if not RTM read the service manual , on topic

this care is ODD
see this chapter in the service manual if opted day1.

Electronic Parking Brake Description tip if ice berg

Vehicles with the electric parking brake have a switch in the center console, which takes the place of the manual parking brake system, the foot pedal and release handle. In case of insufficient electrical power, the electric parking brake cannot be applied or released.
Occasionally, the electronic parking brake will automatically apply when the vehicle is not moving. The electronic parking brake performs a operational check every 50 key cycles. When this check is being performed, the park brake light on the instrument cluster becomes illuminated. This function does not affect the normal operation of the vehicle.
Electric Parking Brake Control Module The parking brake control module has an internal motor, apply actuator, release actuator, and temperature sensor. The parking brake control module also contains the logic for applying and releasing the parking brake when commanded by the park brake control switch. When the parking brake control module receives a signal from the switch the internal circuit board temperature is checked to verify it is within operating range before the control module performs the requested operation.
The electric parking brake module receives hard wired signals from the apply/release switch and communication enable. The electric parking brake module receives wheel speed sensor signals, engine torque, gear information, brake pedal signal, and etc. through GM-LAN.

AND MORE, LOTS MORE, READ THE MANUAL
PAY LIKE i MUST.

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Consult owners manual, check for fill plug about half way up the case. When the oil get to that level that should be plenty.

check wheel bearings for serviceability. Check for brake pad condition.

If the cables are rusted they have to be replaced. try this tip , with the engine running and your right foot on the brake pedal , tap the hand brake pedal with quick jab of the left foot , this may release it .

The problem with your parking brake is there in your question. You never use it so its seized up! Only trained or knowledgeable help is going to unstick it because it may need a rear brake overhaul at the same time. You will have to release the cables to get the rear drums off. Get help. Look up under the dash and see if the release lever is not operating properly. You may be able to trip it with something.

This is a system on subarus to stop you rolling back when on a hill with the clutch depressed . The brakes should unlock as you release the clutch. There is a cable attached to the clutch fork in the engine bay. This goes to a brake actuator on the left hand side. If it isnt working corectly check the cable for wear or fraying. It may need adjusting by a mechanic.

sounds to be electrical issue check make sure your emergency brake isnt down check brake fluid levels do you notice any brake fluid on the ground check gear fluid level

try opening the bleader on the caliper if they release the blake line has an internal kink maybe caused by a recent brake job. if that isnt it it may be the calipers its hard to diagnose without being there in person

FROM LUSTY KID:

Some cars release the emergency brake when you put them in drive, provided you have your foot on the brake first. naturally.

The other possibility, your brake cable is rusted or corroded inside the sleeve and is jammed so it will not release. You might need to replace the whole emergency cable.