If your radio stops responding to controls or freezing it could mean you have a voltage issue. The radio may not have stable power or ground.
In most cases, an incorrect ground will be the cause of most power related issues.
Poor ground or a shared ground with other electronics my cause a drop or spike in voltage. Move the ground to a clean metal point not shared with other electronics or devices.
If there is still an issue:
First using a multimeter, test your vehicles battery with the car not running you should get 12 volts directly at the battery. Turn on the lights and other accessories. If the voltage drops lower than 12 volts, have your battery tested and or replace the battery. Then perform the same test with the vehicle running. The voltage should stay between 12 and 14.9 volts.
If the radio voltage is not stable, voltage may be too high or too low. Test at the radio to make certain both power wires are getting at least 12 to 14.9 volts. Use a digital multimeter, not a test light. Make sure both the RED ignition and the YELLOW constant do not have spikes or drops in voltage at any time. Test when the engine is running and not running.
Keep in mind if you are running a generator and not an alternator you do not have built in voltage regulation. Be sure you are not getting a voltage spike over 14.9 volts.
Other things that may cause the radio to Freeze up.
- Old vehicle wiring. Remember that in most cases, we are dealing with vehicles that are over forty years old, with forty-year-old electrical systems. Older ignitions — such as Lucas wiring — and many other older vehicles simply need to have updated plugs, wires and caps installed. Solid core spark plugs wires offer almost no resistance to RF interference; braided plug wires are best.
- RF (radio frequency) interference caused by HEI or MSD after-market ignition systems.
Inspect HEI: Check for cracked or loose distributor cap. Check for carbon build up. Check rotor for burned black spot-on wiper, or for pits in the surface. Test the coil to make sure it is functioning properly.