Need Installation Manual for 400A Autopilot

[kbecker]

Rick,

DM me your email address and I will send you what I have.

Kevin

[Rick Erwin]

Hi Mark, thanks for the link, however that manual does not have what I'm looking for. I have the Parts and Maintenance Manual, but it does not have the wiring diagrams for the connections to the rest of the airplane that I need.

I appreciate your effort though...

Rick

[Rick Erwin]

Thanks Kevin, DM sent.

Rick

[Dan schultz]

I have the 1974 avionics installation manual let me know which drawings you need. I also have just the wiring diagrams from Cessna

Dan

[Rick Erwin]

Hi Dan,

I have ordered a 1977 Installation Manual for the 400A. If I strike out with the information in that manual, I’ll reach out to see if the information in your manual might help find the three wires I need information on is in yours.

Thank you for the offer!

Rick

[wslade2]

I have a paper manual for a system 400 (not 400A). Includes wiring diagrams. In case that’s any help or they share anything in common (don’t know if they do).

[n86121]

For the most part the autopilot is self-contained within its own harness.

For example, the 'Computer' gets continuous power from the aircraft through a circuit breaker. The control head switch closes a relay within the 'computer' to power it up.
All inside the 'computer'

I just recently got a full Avidyne suite,
and naturally wanted whatever autopilot capability I could get.

One of the mysteries was where/how to interface to a new IFD 550.

ANSWERS:
The autopilot gets its left/right guidance off the CDI.
It gets its climb descent rate by changing pitch on the control head
It holds altitude with an internal pressure sensor within the 'computer.'

I believe I found the schematic for that in the basic 337 electrical wiring diagrams.
Under, believe it or not, the AUDIO PANEL wiring.

WHAT?

The clue was the original audio panel had a DPDT switch to select 'OMNI 1 or OMNI 2"
It had two wires coming IN (for OMNI 1) that came from the original CDI.
As documented in the audio panel schematic.

I had the tech connect those two wires to the new CDI's similar outputs and PRESTO!
C'est voila!
Left right guidance from the new Avidyne avionics.