New Holland T8010 Manual page 1543

Park Brake is stuck on when commanded off
Cause:
The park brake is spring applied. It is hydraulically disengaged when 12 V is applied to the Park solenoid. Fault
code 52 is recorded when the transmission controller turned the power on to the Park relay (Tractor shifted out of
Park and powered off the Park brake) but sensed no power at the Park Brake coil.
Possible failure mode:
1. Park relay stuck open or failed internally
2. No power supply to the Park Relay
3. Wiring or connection to the Park relay has open circuit.
Solution:
1. The power supply to the Park brake relay (relay #5) and the Neutral relay (relay #6) is from fuse #43. If fault
code 52 comes with fault code 37 and the Park Brake will not release when shifted to Forward or Reverse,
check fuse #43.
If fuse #43 is not blown, check wiring between the fuse and the relays.
2. If this fault code comes without fault code 37, replace the Park relay (relay #5) with a known good relay. If the
fault goes away, it was a relay failure. Otherwise go to next step.
3. Unplug the Park relay. Turn tractor off but Key on.
There should be constant 12 V to cavity 3 of the relay seat. If the 12 V is not present, check from the cavity
back to fuse #43.
There should be 12 V to cavity 1 of the relay seat when Tractor is not in Park. The 12 V should disappear when
the Tractor is in Park. If the 12 V is not present when tractor is not in Park, check open circuit in the wiring
between cavity 1 of park relay seat and cavity 4 of connector 350.
There should continuity between cavity 2 and ground. If not, check the wiring from cavity 2 to the ground.
If above checks are all ok, go to next step.
4. Check cavity 5 of Park relay seat.
Turn tractor off.
Check resistance between cavity 5 of Park relay seat and the ground. It should be around 5 to 10 Ohms.
Depress the two brake pedals all way down, the resistance should go to unlimited.
If the resistance is unreasonably high in both conditions, there is an open circuit in the wiring between cavity 5
of Park relay seat and the park solenoid (Make sure the two Bottom of Brake switches are plugged in).
If the resistance is as expected, check for open circuit between the Bottom of Brake switches and pin 28 of
connector 351.
NOTE: Pay attention to damaged harness, pinched wire, or loose terminal to the relay seat.
If there is not a new relay ready available, swap the Park relay with other relays for the checks.
Section 55 - Electrical System, Controller - Chapter 4
FAULT CODE TRANS 52
55-4-16