Very strange, all of a sudden radio only gets power when tranny is in park! Where do I start?

 

Welcome to the forum

What YEAR Ranger??????


Yes, Later models did have a 12volt MUTE for the radio when activated and these did goof up
Radio would still be ON, just no volume, if it different than this let us know

Need the YEAR of Ranger(always) to look up Radio diagrams to see how the 12v MUTE is applied to the Radio

 

 

In 2008 Fuse #22, 5amp, in cab fuse box will have 12volts only when key is in START position, this MUTES the radio

Try pulling fuse #22, in my power diagram it shows its only for the Radio so pulling fuse shouldn't effect anything else

But as to the WHY fuse 22 has 12volts "in gear" is a mystery

Since it doesn't have 12v in Park then could be DTR sensor issue, Digital transmission range sensor is on the transmission, drivers side, but that should cause Check Engine Light and DTR code

So could be problem in Smart Junction Box(SJB) which can be expensive to fix, its the Body Computer

Here is the basic radio wiring diagram
Radios have full time power to hold Presets and current Time, fuse #24, it also powers computer memory and keyless entry
And then key on power Fuse #6, turns radio on when driver turns key to RUN or ACC
Fuse #22 only has 12v in START to MUTE Radio, but...................there were options that mute the radio when Cell Phone rings, i.e. Bluetooth connection, and at other times like in reverse or ???