New Holland T8010 Manual page 1541

Park Brake is powered off when in park
Cause:
The park brake is spring applied. It is hydraulically disengaged when 12 V is applied to the Park solenoid. Fault
code 50 is recorded when the transmission controller turned the power off to the Park relay (in Park position) but
sensed 12 v at the Park Brake coil.
Possible failure mode:
1. Park relay stuck closed or shorted internally
2. Wiring shorted to power.
Solution:
1. 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.
2. Unplug the Park relay. Turn tractor off but Key on.
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 presents when in Park, check shortage to power in the wiring between cavity
1 of park relay seat and cavity 4 of connector 350.
If the 12 V comes and goes as expected, go to step 3.
3. Check cavity 5 of Park relay seat.
Turn tractor off but Key on
There should be no 12 V at the cavity. If there is, check for short to power between this cavity and the park
Brake solenoids.
Depress the two brake pedals all way down. If the 12 V disappears, the shortage to power is between the park
solenoid and the Bottom of Brake switches. Otherwise, the shortage to power is between the relay seat and the
Bottom of Brake switches.
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 COE TRANS 50
55-4-14