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Thread: Head Unit wiring help

  1. #1
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    Head Unit wiring help

    Hey, I'm currently trying to hook up a modern head unit (93 camry) to my corona, there's a bit of wiring involved to get it to work properly.

    The original corona radio plugs are a 3 pin(speakers I assume) and a 2 pin(gnd and acc(12v)).

    My query is: does the new h/u need acc AND batt(+) AND gnd to operate, or can I just use batt AND gnd?

    Any help appreciated

    -Long

  2. #2
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    No you need all three, otherwise with just battery and Gnd it will be power on even when you take the key out, and can drain your battery if you accidentally leave it on.

    With just Acc and Gnd and you will loose presets once ignitions turned off.

  3. #3
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    Quote Originally Posted by RedSunday
    No you need all three, otherwise with just battery and Gnd it will be power on even when you take the key out, and can drain your battery if you accidentally leave it on.

    With just Acc and Gnd and you will loose presets once ignitions turned off.
    Thanks Redsunday,
    At the moment I'm taking +ve from the lighter (can't remember if the lighter was acc or batt now) I'm assuming it was acc, do you know a good place to take batt(+) from? Or should I just run a line right to the battery?




  4. #4
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    just run it straight from your fuse block but just add another fuse.. or is the Sig lighter is 12v constant (12v+ Bat) you can run it from her since the cig lighter is fused.. as for the acc 12+v you can just run it straight from the ignition switch...

  5. #5
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    Quote Originally Posted by arsonist63086
    just run it straight from your fuse block but just add another fuse.. or is the Sig lighter is 12v constant (12v+ Bat) you can run it from her since the cig lighter is fused.. as for the acc 12+v you can just run it straight from the ignition switch...
    Yes, the cig lighter is fused so I'm running 12v const from that, How do I run the 12V acc from the ignition? any pictures and such? I'm a noob at this.
    Also, by taking it from the ignition switch, does it affect anything? (ie. current division)

  6. #6
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    Ok,
    Final piece of the puzzle is finding the best spot to connect 12V acc to.
    I ran 12V acc from the +ve connection of the radio fuse but the head unit seems to be pulsing which is wierd (all the interior lights pulse on aswell).

    Can someone tell me how to wire up acc properly? Any help appreciated :tu:

  7. #7
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    Ok the pulsing aunt good.. You can use the ACC 12v but you need to unplug the original head unit, also it would be best for you to run a new ground to the frame and not from the original wireing. Ps. If you get engine whine you can install a filter on the 12v batt side or just run a wire straight from the batt... Hope it helps

  8. #8
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    Quote Originally Posted by arsonist63086
    Ok the pulsing aunt good.. You can use the ACC 12v but you need to unplug the original head unit, also it would be best for you to run a new ground to the frame and not from the original wireing. Ps. If you get engine whine you can install a filter on the 12v batt side or just run a wire straight from the batt... Hope it helps
    Hey Arsonist,
    Yes, I have unplugged the original unit, I've also tried a different grounding point and also a direct line to the battery, but I still get the weird pulsing

  9. #9
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    Wires I have:



    Alternative GND point:



    Where I've taken ACC:






    Boots up with wierd pulsing, still no sound yet with speakers and antenna plugged in


  10. #10
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    Oh ok hmm... Have you tested the new head unit straight at the bat. (benched tested the unit) before installing it. If it still pulses when bench testing it the unit I bad. Also try grounding the units metal shell to ground (just to make sure you have the right ground wire from the plug), onother thing you can't use the commen ground setup most old units use (meaning 1 neg. Is shared between 2 speakers) so you will have to run new quering to all the speakers. If your using the comeb ground set up with the new unit it will cause the pulsing thing you have going on. Hope this helps you out...

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