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Hello there - I was going to replace my standard Sony Radio/Cassette with a Kenwood cd changer. I got the old one out using the removal keys, connected up the Kenwood (it had compatible plugs) but found it only to work with the ignition OFF! Basically it works with one turn of the key but not when engine running.
I put back the original Sony head and found it to do exactly the same! Have checked the radio fuse and all seems ok. I am mystified.

Does anyone have any clue before I take it to the garage? Much appreciated.

Swap red and yellow wires - this should fix the problem hopefully.

To back up Alex on this one, the red and yellow wires are the memory and ignition [switched] positives, swapping them could well do the trick. Unless you're wiring has really been messed around with then this shouldn't harm anything. To be on the safe side I'd try it with the old stereo first.

Hope that helps,
Steve

Thanks guys, will try that and get back to you.

Tried swapping red and yellow on both head units - no difference. Am even more mystified now.

Im mystified too Check the ignition power fuse?

Am i right in thinking the radio ONLY works when the engine isnt running?

Yup - radio ONLY works when engine off, when you turn key into ignition stage (i.e. when warning lights come on etc) and when car starts the radio dies. It comes straight back on when you turn motor off.

Radio fuses on HU and under dash OK, no other electrical problems.

I've got quite a few people mystified so thanks for reply!

Definately sounds like an ignition power fault or something like that. Umm not too sure what to suggest.

When the engine starts, power supply transfers to the alternator, so it may be an earthing problem.

Your best bet would be to get an auto electrician to take a look. Something like halfords or whatever should know a little more about this kinda problem

Thanks for help, though was trying to avoid H'fords. The annoying thing is, the radio works, the ignition works, just not together!