Notification on GNC355?

[jd21476]

I had a GNC 355 installed with a GMU11 and a GAD29b along with a G5 HSI. I keep getting these two notifications on the GNC355.

1. “Heading source inoperative or connection lost”

2. “Pressure altitude source inoperative or connection lost”

Unfortunately the avionics guy who did the install is no longer around so I cant go back to him.

Is this notification wrong or donI need to fix something?

 

[murphey]

From the POH: (If you don't have this document, go to Garmin's website and download it)

Advisory: “Heading source inoperative or connection lost”
Condition: <Unit> is not receiving heading information from any source. Heading up map orientation not available.
Corrective Action: Contact dealer for service.

In other words, find the nearest Garmin dealer to fix it.

 

[mondtster]

I don’t have personal experience with interfacing a G5 to a GNC355 but I have some experience interfacing other Garmin products. It seems as though there is no communication between the g5 and the GPS. Have you been messing around in the configuration of either box lately? Perhaps the communication setup is screwed up.

 

[jd21476]

I haven't been messing around with the settings but Ill look into it.

 

[nrimmer]

Did this randomly happen or has it done this since initial install?

For the heading issue check the install manual to be sure the output settings on your G5 and input settings on your GNC 355 are correct. I believe the G5 sends GMU 11 heading info to the GAD 29 via the CANBUS, and the GAD 29 sends that info to the GNC 355 over ARINC 429.

It doesn’t sound like you have a pressure altitude source hooked up. My GNC 355 only gets pressure altitude from the GAE 12 altitude encoder that is part of my GTX 335 transponder, which talks to the GNC 355 via RS-232.

With that said I don’t think your GNC 355 needs either heading or pressure altitude to function properly as a GPS.

 

[jd21476]

Its been since install but unfortunately the guy who did the install has passed away so I don't have any follow up available

 

[Salty]

Did this randomly happen or has it done this since initial install?

For the heading issue check the install manual to be sure the output settings on your G5 and input settings on your GNC 355 are correct. I believe the G5 sends GMU 11 heading info to the GAD 29 via the CANBUS, and the GAD 29 sends that info to the GNC 355 over ARINC 429.

It doesn’t sound like you have a pressure altitude source hooked up. My GNC 355 only gets pressure altitude from the GAE 12 altitude encoder that is part of my GTX 335 transponder, which talks to the GNC 355 via RS-232.

With that said I don’t think your GNC 355 needs either heading or pressure altitude to function properly as a GPS.

in his system, I’d think the pressure altitude is coming from a G5 with a static line hooked to it.

 

[Jesse Saint]

You have a bad ARINC output from the G5 to input on the 355. Missing wire, wrong pins, swapped wires, etc. should be fairly simple to ring out the wires between the GAD29 and the 355.