When I fitted my stereo, I never had the Autoleads ISO block as they had none on the shelf and I had t ohave it fitted then!!
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Soon discovered about balanced system.
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In short, front speaker wires are always in pairs
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(white/white with stripe and grey/grey with stripe), rear speakers
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(green/green and stipre and purple/purple and stripe), amp/aerial remotrew power is blue
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(can be blue with white stripe), dimmer is usually brown or orange.
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When you come to the original wiring however, this is something that even the Sphinx couldn't know.
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Assuming you can get the unit to power up, but have no sound, it could be that the speaker cables aren't connected properly, which could be a result of the factory fitted pre-amps behind the passenger side panel trim.
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I know this is daft, but did you have a working stereo in before you tried to fit the new one?
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Having just read your post properly, have you tried running the phono connectors into an amp? Normally phono leads carry a voltage which, and please correct me someone if I'm wrong, would probably not do the standard amps any good.
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Try to connect to an external amp and connect some speakers to that
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(with low volume so as not to blow them).
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If you get a sound then, then you need an amp.
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