I have a 1988 F-150. It has an aftermarket Kenwood radio. I pulled it out and T tapped the illumination wire that brightens and dims the lights. It did get unplugged from the thick cord that plugs into it. Now that it’s plugged in and I ran the truck to bleed the coolant. And it now says protection. Any idea what this is?

 

Sounds like anti theft protection built in the radio.

Google the model # for a manual.

 

I have never seen a Kenwood that needed a code but...

 

It could have overheated?

 

I did some research it just had to be reset for some reason