Sorry about duping this, but as this forum is divided to Ford / Mercury, I'll post this on both as they are identical on this...

Anyway, our 2006 MMH has a factory Nav-radio. The Nav is useless over here in Scandinavia (no maps available even from Ford) and radio only picks half the stations due to 200 KHz resolution between stations. (We use 100 KHz resolution here.) But the CD (and the 6-pack) work fine and the display shows nice MPG-graphs, so we've kept it.

But now the radio seems to come on byitself! It has run down the 12 V battery down twice during the night. For temporary fix, I've taken out the fuse, but that also is the fuel gauge fuse that sets a DTC for the emission system. So no good there either.

Question is: Has anyone come across this before and know the cause for it?

Please, no "take it to Ford" answers. Not gonna do it. I'm now looking for answers to the cause of the issue...

 

I don't have this issue and can't track the problem down. I can offer a suggestion for the symptom of 12V battery running down. Install a trickle charger on your vehicle and plug it "on" each night to counter any possible drainage of the 12V battery.

 

Thanks for your input. I've been considering could the problem actually just be an old 12 V battery, as low voltage can trigger funny incidents with computers. And the battery IS old, so I might swap it anyways...

Unfortunately the trickle charger is not really a solution, but bandaid to a broken leg. Specially as it won't do no good when parked at the office - no power outlet available here. So, for now I gotta take off the fuse. If I only take it off while car is switched off and reinstall it before next drive, the car doesn't test the fuel circuit and won't notice the fuse having been off. - Works as the temporary bandaid on the broken leg, until I find the cause...

An other idea I have is bad grounding somewhere in the dash. This would cause the dash to ground through the radio and thus triggering it on. Quite a common issue on these new "Nintendo-cars" with miles of wiring and pea-counters thinning out even the grounding leads to a single thread...

...and only just this morning the car came up with a new symptom. It switched on high beam when I put on the turn signal. Double checked that I didn't push/pull the lever accidentally, but no. And after a couple of seconds it switched back to low beam by itself.

This could be because a bad ground somewhere. Have to have a look at the wiring charts... ...but I guess I should also change the battery in any case. And while at it, maybe I should change the MECS-pump, a tie rod end and a wheel bearing that both seem to be a bit on the loose side... ...just swapped an ABS ring & sensor. Why do these problems always seem to pile up?

 

That sounds like maybe your smart junction box is acting up if the 12V is OK.

 

You don't have to pull a fuse, the head unit has an on/off "switch"....push the volume button.