I have a Sony Air 7 radio. The volume control is faulty, it only works at full volume. I have taken the back off the radio but can't access the area around the volume button.

Recently I found a Sony ICF 7600GR with same issue.... Radio runs full volume.. can't be controlled... Found a SMD package capacitor C252 ,1uf was short.. 1.2Volt was missing on pin number 14 of IC 203

Check these voltages of IC 203 ( CXA1522P)
Pin -15 Voltage is 1.3V
Pin -14 voltage is 1.2V then" No/low Volume".
Pin -14 voltage is below 0.5 then "Full Volume ".

By varying volume control (RV204 , 50K) , Pin number 14 of IC 203 must vary between 0.3V to 1.2V.

You do not mention the type of Motorola radio so this answer will be general. You may have a problem with your volume potentiometer, Receive (Rx) sensitivity, or a speaker problem.
The volume pot on a 2-way radio is a common failure item, and will after repeated use possibly fail, or get dead spots. Try backing off your volume to 75% and see if it is louder at this setting. If so, you have a bad volume pot.
Rx sensitivity can be caused by various internal problems with the radio,and some models are more prone to this than others. Operating your radio at full volume most of the time can bring this issue to the forefront. (Tip: Try running your radios at 80-90% volume vs. full volume to alleviate this problem.) If this is your issue, your effected radios are in need of repair. Most repair facilities (including ours) can correct Rx sensitivity in most models during a repair.
Speaker problems: If you work in an environment where dirt, debris or metal shavings can get inside the speaker, your speaker may fail over time. Or if you run your radio at full volume the majority of the time it can cause your speaker to fail.
Best regards.

Radio volume control on 2008 Subaru Tribeca does not ...

www.fixya.com/.../t25735073-radio_volume_control_2008_subaru_trib...

Jun 7, 2015 - Radio volume control on 2008 Subaru Tribeca does not work, but remote volume control on steering wheel works. ... does not... Replace the volume control(rheostat) inside the radio. .... Oct 09, 2014 ' 2007 Subaru B9 Tribeca.

Just try to spray contact cleaner in it thru volume control knob area by removing knob outward.The proper way is cleaning by spraying in the audio control switch from inside but because it is bit difficult job,Hope it will solve the issue.

The volume controll is wore or dirty on the contacts in side of the switch youll have to probley have to get it replaised to cure the problem.

This is cause by many things one of which is a faulty speaker that is going short when operated at high volume. Another is the wiring supply the power to the radio is not "thick" enough hence not able to supply the demand for extra current. Had this same problem with Golf II which I replaced the main supply wire and after that it went to full volume with no cutting off.

The passenger controls on the rear speakers are pretty easy to diagnose.  The wire for Volume up is Pink/white, the volume down is gray/white.  If the Pink/white wire is shorted to ground somewhere, then as soon as you turn on the radio, it will be like having the volume selector pushed up, and it makes sense how you describe it goes to mute and then returns to full volume as soon as you let go.   You don't say what model it is (I doubt it's a Road Glide, gotta be an Ultra), so it's not too hard to get at.  Pull the outer fairing and look on the back of the HK Radio.  There are 2 big connectors, when looking from the front you want the connector on the right.  Pin 23 is down volume, pin 34 is up volume for the rear controls ONLY.  So I would check the continuity to ground at pin 34 first, in other words pull the connector off the back of the radio, take a test lead and hook one end to +12v. Touch the tip to any grounded metal and it should light.  Now touch the tip to pin 34 on the harness side of the connector.  If the test light lights up, you have a short to ground on the pink/white wire.  Now go to the right rear speaker on the tour-pak and disconnect the 6 pin connector and try the test again.  The pink/white goes from pin 34 on the radio and runs through the harness to the passenger controls and nowhere else.  It shouldn't be grounded anywhere.  Let me know what you find out. 

This is a very common problem with this radio there is a part in the radio that controles volume and it breaks down after a period of time due to vibration... If you need any repair help you can email me at [email protected] I no these radios inside and out and would be happy to help you- thanks

Sony CDX-GT300 volume control stopped working. Radio is either on full-blast, or you have to turn it off. Any solutions? Thanks!

akon