New Holland M153?

You mean error code 6 for 3 pt.
Slip control voltage low(short or open circuit) for Power, Range & Dual Command Transmissions.
Check the wiring & connectors is all that you can basically do, as you will need a multimeter & know which connectors to check the resistance of the EDC control panel which should be between 80-340 ohms when turning the slip control fully clockwise otherwise it's faulty.

Warren
February 2011