Billy Dean
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Registered: 5th Jan 10
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I've been having a bit of trouble with my aftermarket Sony Head Unit for some time now.
I bought the car with the HU already 'installed'.
For the first few months the HU would work OK. Then it went a few months by turning on sometimes and staying off at other times, i.e. behaving as if the power wire was popping in and out every few days!
And now it just won't come on at all!
Sooo, I finally got round to taking it out this afternoon. I took a photo as below. All fuses intact and good.
I put the multimeter on the car's ISO.
Position (1) shows the meter on the fat brown and fat red wires. Readings were about 12.5V engine off, and about 14.5V engine on.
With the engine on, no other wires would give a reading apart from the pin at the bottom left (circled (2)) which gave a reading of about 12V. So I assumed that that wire was the HU switching wire from the car.
But when I looked at the HU's ISO harness there is no wire that matches up with the "switch on" wire from the car.
I circled the relevant wires on the HU's ISO in green. Whilst the black and red wires match up with the positions on the car's ISO, the yellow wire matched up with a pin on the car's ISO that had no voltage reading!
Also an important point possibly. The HU's ISO had not had its red and yellow wires swapped over since I bought the car.
I swapped them over today via the bullet connectors.
[img] Uploaded with ImageShack.us[/img]
So what is going on here??
Is the HU ISO wired incorrectly? If so, is that why the HU has been temperamental since I bought the car?
Or do I need to buy a different HU ISO?
Or something else??
Your help is very much appreciated.
I am very new to car audio electrics!
p.s. using my VERY basic knowledge of car electrics, I have a gut feeling that the problems have occurred due to the red and yellow bullet connectors never having been swapped over. The fuses have not burnt, but maybe high currents in the wrong wires have damaged those wires irreparably? The wires in the HU's ISO in any case do not look like they match up properly with the relevant wires in the car's ISO. It seems weird to me anyway.
[Edited on 11-03-2012 by Billy Dean]
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Gary
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Registered: 22nd Nov 06
Location: West Yorkshire
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upload.wikimedia.org/wikipedia/commons/thumb/3/34/ISO_10487_connector_pinout.svg/220px-ISO_10487_connector_pinout.svg.png
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Billy Dean
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Registered: 5th Jan 10
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Thanks for the reply.
I had a look at the diagram you posted.
What does it mean with reference to my HU?
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Billy Dean
Member
Registered: 5th Jan 10
User status: Offline
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Anyone?
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Bmorgan1993
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Registered: 28th Sep 11
Location: Gloucester, Gloucestershire
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Tbh mate if actually have to be there to help you out but best bet is replace the unit, or check all the wiring.. as in follow it, also if you have a haynes manual it will tell you which wire is which follow that guide to make sure all your wires are in the correct location in the ISO. However the fact you said its only start playing up after a few months sounds like your head unit is FOOKED but this is all my opinion i am in no means a stereo expert however this is what i'de do .
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Eddx14xe
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Registered: 12th Jan 10
Location: Hertfordshire
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Have the manual for the head unit? Wire 2, that comes on with the ignition should be the ignition live. If this isn't connected to the head unit then it wont work. The ignition live cable on the head unit is usually the blue on, so you would have to swap the pins over in the iso.
Don't hold me to the ign cable being blue though, need to check it in the manual first or just try it depending how brave you are and how much you want that head unit.
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harvey_1066
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Registered: 9th May 10
Location: Ludlow Shropshire
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have you tried swapping the wires in the harness so it turns its always live so you have to manually press the button on the radio to turn it off?? that might be worth trying as on my old corsa the switched live from the steering wheel area must have been dodgy as i remember if i pushed / twisted the wheel a bit funny the radio used to turn off lol but then i put both the constant live and switched live to the constant live and never had any problems again apart from having to remember to turn the radio off.
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Billy Dean
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Registered: 5th Jan 10
User status: Offline
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Thanks for all the suggestions. They have given me food for thought.
There is one thing I need confirmation on - is my car’s ISO wired up correctly??
When you look at the photo above:
Top-right pin = thick brown wire
Bottom-right pin = thick red wire
(These pins give 12V and 14V readings when ignition is OFF and ON respectively)
Bottom-left pin = blue and red thin wire (this gives a 11.3V reading when ignition is ON)
Top row, 2nd pin in from left = thin red wire (no voltage reading at any time).
ARE YOUR CAR'S ISO'S WIRED THE SAME AS THIS?
(on my other car (Astra mk4) the fat red and black wires are perm live. With the thin red wire being switching live).
[Edited on 15-03-2012 by Billy Dean]
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