How about a better explanation of what you mean by "lost"?

What device are you plugging into the AUX jack?
Is it a known working device on other systems you've plugged it into?
Might also check to make sure you have a good quality cable.

For aux to show up as an option, you must have a working device plugged in.
Otherwise, I don't think you will even see an option for aux (going by memory here)

 

2 posts so you must be new with the bike.
Speaker swith is three position.


If it's in the wrong position, might be your problem.


Radio still works, right?

 

 

My stock radio would do this from time to time, the only way I could get it back was to leave music player plugged in and turned on playing music then shut the bike off and restart. Sometimes it would take a couple of restarts to see it.

 

If it were mine I'd spray some contact cleaner into to e aux Jack and work the plug in and out a few times hoping to clean the contacts.
If that failed I'd consider sending it to Iron Cross for repairs and upgrades. Or an aftermarket radio.

 

Well, that tells me your Radio is not recognizing the device you have plugged in.

You didn't list what that device is though?

Try another device, or as ORradtech suggested cleaning the contacts.

You won't have "AUX" show up in the display if you don't have a recognized device plugged in.

 

Try putting the plug in an extension, then plug the extension into the radio.

 

It's not uncommon for one or more of the three solder tabs on the 3.5mm jack to break free from the PC board. If your device is known to be working and you've tried different 3.5mm patch cords that have also been confirmed to be functional and the previous suggestions aren't providing favorable results then the radio needs to be removed from the bike for the repair. If you can solder you can fix it yourself. Just remove the face plate and you'll see the three tabs. Ground is in front on the right and that's probably where your problem is. This ground connection and at least one of the other two needs to be solid or the radio won't recognize the source and activate the Aux option.

Take a look at this link and scroll down to step 10 for a visual of the tabs. https://www.ironacesspeedshop.com/ha...vidson-stereo/