Expert: Peter G. Lee - 8/8/2006

Question
I don't have access to a digital multimeter, but when I put the original head unit back in the car (a Blaupunkt) it switches on when I turn on the ignition, and off again when I turn it off. Does this prove that there is (a) power in the accessory wire and (b) no grounding issue?
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Followup To

Question -
There's a fuse right next to the multi-adapter on the rear of the JVC - I removed and checked this and it looks fine. No other in-line fuses in the cables.
If a fuse had blown, would that not have prevented the disc accept/reject mechanism and clock to also fail? (these both work fine).
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Followup To

Question -
I'm having problems with a JVC KD-DV6201 head unit fitted in an Alfa 147. I had the unit installed and working fine, then one morning it wouldn't power up.
I know that there is power getting to the head unit: If I press the "disp" key on the front panel of the JVC the clock on the head unit would illuminate for a few seconds, then go out.
It will also accept and reject discs without any problem. It just won't turn on - with the ignition turned on or not.

The original Alfa head unit (a Blaupunkt) works fine - powers up when I turn the ignition key.

The previous evening I had been trying to adjust the unit because it was protruding from the cage, but wasn't aware of damaging anything.

I returned the JVC to the supplier (it's only 2 weeks old). They say they tested it and found no problem - had it running "all afternoon" - and returned it to me.

Could you offer any advice/suggestions?

Answer -
Sounds like a blown fuse in the harness for the JVC. Some have in-line fuses in plastic covers. Check for +12VDC (or some voltage) right at the head unit plug with a multimeter, with the key on. Check for a broken ground wire too.

Answer -
Those other functions run off the memory fuse. Check that there is power on the accessory wire with a digital multimeter.

Answer
you don't always need a multi test meter (but it is best) a 12v bulb in a holder with a couple of wires will do just as well if carfull.
yes it should do as it is. on and off with the ignition, (+15)
you should have three 12v cables,
1 = 12v perm from fuse bix
2 = 12v acc, from ignition (fused)
3 = 12v OUT od radio for electric areils, amps etc.
plus earth and possibly a wir from the side lights to opperate the facia dimmer
Hope that helps.
Peter