Strange electrical fault - help needed

[Al U]

So when I put my sat nav or iPhone charger into the 12v socket inside my car my aftermarket sony mex-bt3900u stereo switches off. As soon as I take the charger out the stereo comes back on. So it's no music and use the socket or have music and don't use it. Very annoying, anyone heard of this before or know how I can sort it? Thanks.

Edited by Al U on Saturday 13th December 21:03

[RedBull]

Without being able to take a look at it it's only possible to speculate. For me the key word in your post is "aftermarket". I would check the wiring of the unit as it may be that the power supply is taken from the lighter socket and when the socket is in use there is insufficient supply to the ICE unit. That of course would mean a badly installed unit, but it's the first thing that came to my mind.

[Al U]

Stereo is wired into the main harness behind the stereo with a proper iso connector. I've checked that and nothing looks unusual. When i say aftermarket I don't mean anything radically custom just a non manufacturer fitted unit. I was hoping it was a common problem and someone will know what it is.

Edited by Al U on Saturday 13th December 16:03

[loafer123]

At a guess the cigarette lighter socket is drawing sufficient power from the system to cause the stereo power to drop below acceptable levels, so it cuts out to protect itself.

[grayze]

Does using the cigarette lighter switch off the stereo?

[Al U]

grayze said:

Does using the cigarette lighter switch off the stereo?

Car doesn't actually have a cigarette lighter as such it's a 12v socket but I have always called it a cigarette lighter socket.

Edited my op to say 12v socket.

Edited by Al U on Saturday 13th December 21:04

[DKS]

loafer123 said:

At a guess the cigarette lighter socket is drawing sufficient power from the system to cause the stereo power to drop below acceptable levels, so it cuts out to protect itself.

I would go with this. The wife has a similar quirk in our 1.3 Mk2 Astra. New flash Kenwood stereo works very well, and can even kick 2A out of its USB sockets. The main memory supply is taken from the hazard switch for some reason on that age Astra. When she uses the hazards for saying thank you when let out at junctions for example, it makes the stereo restart.

[Bill]

Sounds like a dodgy earth somewhere.

[Al U]

Bill said:

Sounds like a dodgy earth somewhere.

I thought this, but where do I look?

[Bill]

No idea, I'd start at the easily accessible bits like the main earth strap.

[Al U]

DKS said:

loafer123 said:

At a guess the cigarette lighter socket is drawing sufficient power from the system to cause the stereo power to drop below acceptable levels, so it cuts out to protect itself.

I would go with this. The wife has a similar quirk in our 1.3 Mk2 Astra. New flash Kenwood stereo works very well, and can even kick 2A out of its USB sockets. The main memory supply is taken from the hazard switch for some reason on that age Astra. When she uses the hazards for saying thank you when let out at junctions for example, it makes the stereo restart.

So what's the answer then, bigger battery? May I also add that it hasn't always been like this it's only recently started happening which makes me think a bigger battery won't help.

[Al U]

Bill said:

No idea, I'd start at the easily accessible bits like the main earth strap.

Is that the one from the battery to the body? I know my way around cars but not when it comes to electronics.

[Bill]

Yep, and there's probably one between engine and body. Take them off, clean them up and see what happens.