For some reason it sounds like the aerial amplifier(s) under the rear shelves are only getting power when the ignition is off. Anyone been playing around with the wiring?

 

Not to my knowledge no... but now you mention it the PlayStation stopped working too and that's in the boot - I now wonder if those two issues may be linked. Good thought, I'm going to do some more digging...

 

"What on earth is going on" is probably close to the reason. Check earths on the radio and the amplifiers in the back.

If the HEVAC display dims slightly when pressing the brake pedal as well, then one of the earth splices behind the dash could also be faulty. Mine does this but luckily it doesn't impact the radio.

 

As a Playstation wasn't originally installed, someone has been playing with the wiring. I suspect they've connected it in with the feed to the aerial amp(s) and there's a high resistance joint lurking somewhere.

 

I’m having exactly the same issue on my 2001 HSE. I find that if I turn everything off and leave it alone for a few minutes and come back, I can repeat the process with starting to turn on the radio with all the amp/dsp working as as volume control. But as soon as I turn the key on the amp drops and locks the volume

prior to this I was only able to work the radio with the lights turned on. When I pulled out the gps head the whole thing started to fail on all levels. Help!

 

Just a quick update on this, I reached out to Richard L and he suggested making sure the NAV system was completely removed from the situation. Once I did this I was able to return the system to full function!
Hope this helps as the NAV system has a mute function for both the GPS and any other function like phone system.

 

Hi Everyone, Just joined to post my recent radio experience. I purchased my Yr2000 4.6L P38 in July 2021 with known problems. The battery drained in about three days and I traced that fault to a dead Sat Nav which I disconnected by pulling the plugs from the back of the box installed in the rear RH quarter of the car. The battery has been fine ever since. The radio has always been temperamental. Sometimes on, sometimes off needing the Code again. However, two days ago, I started the car and the radio self started at full volume. The On/Off button and volume control didn't work so I could not shut it off. Brilliant anti-theft device, but crap as a radio. So with two thick, plastic tie-wraps and a bit of wriggling, I removed the radio to look for frayed wires or anything obvious. I eventually took the Alpine unit apart looking for any dodgy soldered joints and found one which was A) Crap and B) Broken. Alpine thought it was a good idea to solder a thick metal chassis tab to the metal can of the R.F. receiver. Needless to say, this soldered joint fractured and electrically disconnected the frame from the R.F. case. From a production perspective, this is SH1T and Alpine should be ashamed of themselves for using this crap technique on expensive production units. I repaired the joint with a short length of copper braid used to remove old solder from pcbs, etc. I reassembled the radio and re-installed it in my P38. It now works fine, with both volume and On/Off control restored. For all those out there with weird radio problems, it could be caused by the same crap soldered joint between metal to chassis inside the Alpine radio. I can't offer any other advice because I only have a sample of one radio, i.e. mine, to go on. However, this broken soldered join would have explained all the other strange behaviour with my radio for the last five months. I hope my notes help.