2006 Ranger i have audio in on position only with engine not running. radio has power in aux position, has all functions, no audio. If you start the engine the radio has all function, but no audio. I have replaced the ignition switch no change.

 

If the radio powers up and has all functions but no sound its either a problem in wiring to the speakers or the internal amplifier. But if all speakers are out then its most likely the amplifier the odds of all speakers failing completely at the same time are pretty low. Looks like time for a new head unit.

 

Then why does the audio work when the key is in the on postion

 

interesting usually the switch only turns the head unit on it has a constant hot and a switched power line from the ignition switch that tells the radio to power up. If its coming on at all then the ignition switch and those components are working as designed. Id have to do some checking its possible its a body control module issue not supplying power to the speakers in the on position but i can't remember if it has that power or not.

 

Couldn't find any direct info on the BCM but i found another thread that talked about the grounds. Do you have the tools to pull the head unit out? It should have a grounding strap and and a black wire ground in the actual harness which can cause intermittent issues with functions depending on how much load is applied to the electrical system. (i.e.. running vs. acc.) might be a good idea to start by checking your grounds behind the radio and at the battery. These trucks have a lot of sneak circuits and one bad ground could cause all sorts of odd behavior.

 

You would think if it were a ground problem it would be persistent in all positions. It had this problem once before and only had audio in the Aux position on the ignition switch. It will eject the disk and accept it, show the footage, will change positions on the disk, change to radio position. if you go to cassette it will say you have no tape. works perfect in the on position.

 

found the problem, it was the relay in the smart panel (fuse panel) passenger side kick panel. The first time i unplugged it the radio had audio in the start and acc but not in run. unplugged it again and then had audio in run. Happy camper