My truck radio seems possessed

I can’t figure this out. Almost all but not every time I start my 2002 Avalanche my car radio is off and displays a different time than the actual time. I will turn the radio on, reset the the clock and go about my drive. Park the car, turn off ignition, take out key, go to work, store, etc… Come back to vehicle, start it, radio is off(I never actually turn it off) and the time is a totally different time again. Do I need a new radio or a exorcist? This has been an on going issue for months. At one point I did replace the battery, it was actually bad(old) so I don’t think it has much to do with the problem. Is it a electrical issue, the mechanic I took it too said no, went to another, again no problem there. Any help would be GREATLY appreciated.

Also, the presets stay the same, I don’t lose them.

I had the same problem on my 1990 Aerostar. Sometimes, when I would start the vehicle, the clock would revert to 12:00. However, it didn’t lose the radio presets. My guess is that the radio isn’t receiving full power from the battery due to corroded connections someplace or the battery may be going out.

If this isn’t the case, I would buy a stick-on clock for $5 from the discount store, put a piece of tape over the clock and call it fixed.

I think there’s a wired steady connection between the radio and the battery. Find it, clean up every connection, follow it through the fuse box and clean everything.

As mentioned above, the radio probably has two power connections. One is only hot when the ignition is turned on (or acc, if you have that). The other is hot all the time. I suspect there’s something wrong with that. It could just be a fuse. A mechanic would back probe the connector to see if it is actually hot or not. If it is hot, and the radio still misbehaves, its probably something internal to the radio, and replacing the radio is probably the best alternative.

Edit: There is usually something called a “noise suppression” capacitor somewhere. Often in the ignition system. Unlikely, but that could be the problem too. It’s difficult to diagnose is the problem. Usually if suspected, it would just be replaced and see if it fixed the issue.

Usually if there is a problem with the memory power for the radio the station memory is effected also. The trouble might be with the clock circuit itself. Verify that the 12 volt memory power is getting to the radio okay. If that is okay then you may need to replace the radio. Ebay is a good place to find used OEM radios for a good price if you want to go that route.