The Autopilot (A/P) can control the aircraft in a climb, cruise decent and approach phases of flight or as directed manually by the pilot via the control knob. It may also be directed by signals from the VHF, GPS, INS navigation systems. It can also find and maintain a pre selected heading, altitude, pitch attitude or operate in a split axis configuration.
It requires 115V AC for operation from the aircraft generators or an external source. If using the latter you need to operate the ground test switch.
Electrical interlocks prevent selection or operation unless all the proper conditions for correct functioning are satisfied.

INTERLOCKS
Mandatory interlocks are at least one yaw damper switched on and it's disengage flag out of view, turn and pitch controller in neutral detent, operating vertical gyro if these conditions are correct you will be able to engage the aileron switch. To engage the elevator switch the aileron switch must be engaged and the cruise stabilizer trim switch must be in the normal position.
The auto pilot will disengage if any of the following actions or conditions occur. Yaw damper positioned to off, capt or co pilot press autopilot release switch, power to vertical gyro is lost, switching compass source or power to A/P aileron  (roll) is lost. Elevator channel disengage will occur if the stabilizer trim switch is activated, pitch channel selector is switched (A or B) cruise trim switch is activated, A/P and cruise trim cutout switches positioned to cutout, electrical power to the A/P elevator (pitch) is lost.
A/P mode will return to manual (turn and pitch knob) if any of the following occur reference VHF/GPS/INS is switched, turn and pitch controller moved out of detent, ILS frequency is switched while in approach mode.