New Holland T8010 Manual page 1472

12VD Voltage Supply is Below 8 Volts
Possible failure mode:
1. Battery voltage is too low.
2. Alternator regulator malfunction.
3. The controller has a bad connection to power or is not grounded properly.
Solution:
Check for battery voltage, fuse #39, alternator regulator output, and the controller connection to power and ground.
1. Check for AUX/Hitch/PTO fault codes 65, 66 and 99. These are all fault codes for low voltage supply. If they
exist, it is most likely that the battery voltage is low.
2. Test battery voltage. It should be around 12 - 14 volts.
3. If the battery voltage is OK, check system voltage at cavity 8 of connector C053 at AUX/Hitch/PTO controller.
Check for bad connection and improper ground at cavity 19 of connector C053 at AUX/Hitch/PTO controller.
Check for shortage to the ground along the power supply to the controller.
4. Test alternator output if the battery voltage would not hold even when the tractor has been running.
The voltage should be above 14 volts at C077 - B+.
5. If none of above, check the function of the AUX/Hitch/PTO controller.
NOTE: See schematic sections 49 and 50 on the schematic poster.
12VT Voltage Supply is Below 8 Volts
Possible failure mode:
1. Battery voltage is too low.
2. Alternator regulator malfunction.
3. The controller has a bad connection to power or is not grounded properly.
Solution:
Check for battery voltage, fuse #39, alternator regulator output, and the controller connection to power and ground.
1. Check for AUX/Hitch/PTO fault codes 65, 66 and 98. These are all fault codes for low voltage supply. If they
exist, it is most likely that the battery voltage is low.
2. Test battery voltage. It should be around 12 - 14 volts.
3. If the battery voltage is OK, check system voltage at cavity 25 and 34 of connector C054 at AUX/Hitch/PTO
controller.
Check for bad connection and improper ground at cavity 19 of connector C053 at AUX/Hitch/PTO controller.
Check for shortage to the ground along the power supply to the controller.
4. Test alternator output if the battery voltage would not hold even when the tractor has been running.
The voltage should be above 14 volts at C077 - B+.
5. If none of above, check the function of the AUX/Hitch/PTO controller.
NOTE: See schematic sections 49 and 50 on the schematic poster.
Section 55 - Electrical System, Controller - Chapter 3
AUX/HITCH/PTO FAULT CODE 98
AUX/HITCH/PTO FAULT CODE 99
55-3-53