AXP340/322 ADS-B Transponder - Why doesn't my AXP340 power on automatically?

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Why doesn't my AXP340 power on automatically?

Printed From: Avidyne
Category: Avidyne General
Forum Name: AXP340/322 ADS-B Transponder
Forum Description: Topics on the Avidyne AXP340/322 ADS-B Transponder
URL: https://avidynelive.com/forum_posts.asp?TID=1229
Printed Date: 26 Mar 2026 at 2:12pm
Software Version: Web Wiz Forums 12.07 - https://www.webwizforums.com

Topic: Why doesn't my AXP340 power on automatically?

Posted By: LANCE
Subject: Why doesn't my AXP340 power on automatically?
Date Posted: 20 Feb 2017 at 12:51pm

The Pilot's Guide for the AXP340 on page 4 says, "The AXP340 will automatically power on when avionics power is applied and will display the Avidyne logo, product identification and software version information while the unit is self-testing."

Mine has to be manual powered on. Is there a setting I can change - I don't see anything in the book on this?

Replies:

Posted By: Gring
Date Posted: 20 Feb 2017 at 2:05pm

There is some wiring that will turn it on when the avionics bus is powered. Check the installation.

Posted By: LANCE
Date Posted: 20 Feb 2017 at 2:28pm

I should have mentioned that it did power up automatically when it first was installed, but now doesn't

Posted By: psimpson
Date Posted: 21 Feb 2017 at 5:32pm

My first one acted that way, they had to replace it. It's fine now

Posted By: LANCE
Date Posted: 24 Feb 2017 at 1:34pm

I was at the avionics shop today for another reason and told them about it. They called Avidyne and Avidyne said it may need to be exchanged but told the tech that if it gets shut off manually it needs to be turned back on manually. He fiddled with it and there's nothing in the settings, but now at least it comes back on automatically. We'll see if it stays that way.

Posted By: LANCE
Date Posted: 21 Mar 2017 at 7:40pm

Well, it didn't stay that way. Now it needs to be turned on again manually every time I start up the airplane.

Posted By: M20J
Date Posted: 23 Mar 2017 at 9:08am

Mine also did that, I had it exchanged and the replacement works correctly. Get it replaced.

Posted By: psimpson
Date Posted: 23 Mar 2017 at 1:37pm

Mine did the same thing, once I got another one it has been fine since.

Posted By: LANCE
Date Posted: 21 Jul 2017 at 12:31pm

I brought my airplane in to have the heading source tied into the IFD550 so I can get the Total Velocity Vector. I talked to support weeks in advance about my transponder not powering up with the Master. They agreed it needs to be swapped out. I let my avionics dealer know. They were supposed to have a swap for my on July 17 when I took it in. The dealer dropped the ball and forgot - Avidyne to the rescue - they overnighted one and it was put in before I even knew about it. Once again, great Avidyne service!!