Check for voltage on all the fuses. The radio is likely dead because the memory circuit is tied in with the interior lights.

Is there any history that led up to this? Do you have the manufacturer's service manual with the wiring diagram?

Answered by caradiodoc (expert)
17,256 answers provided

Thanks, I will.
I purchased the Jeep on Saturday. Everything was working.
I took it in to get a detail and shampoo as it was very dirty. When I picked it up, the problem was noticed. As well, the headlights and dash dimmer work, but the interior light (turning knob to left) does not. Could this be a coincidence?

Response from binderdundat
1 question asked

The radio's memory wire is tied to the interior lights fuse so if the lights don't work, the radio won't either, depending on the model. Some need that memory feed to even turn on. Some will tune but won't have any sound when that memory circuit is dead. Some radio models play fine but go back to 12:00 and the station presets go back to factory defaults after they were turned off.

With all the systems you listed, the first thing I'd check is the large fuses under the hood. They will typically be 30 and 40 amps cartridge fuses. For the smaller ones there are two tiny holes on the top to stick the voltmeter or test light probe to check them. You're looking for one that has voltage on one side but not the other. Fuses with voltage on both sides are good. Fuses with 0 volts on both sides can be ignored. Those circuits are turned off. You know those aren't suspect because the power locks, power mirrors, and interior lights are always live.

Also test inside on the fuses for the individual systems. I expect you'll find no voltage on all the fuses for the dead systems. That points to one problem with the under-hood fuse that feeds all those inside fuses, not a bunch of individual problems and blown fuses.

Answered by caradiodoc (expert)
17,256 answers provided