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Aftermarket Headunit Requires Ignition Feed


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Hi Guy's,

Would appreciate any help on where the best place to get ignition feed for my head unit would be.

I've fitted a JVC sat nav double din headunit using the autoleads amp bypass harness, the unit works well and will look good once the facia is sorted out as per Wozza's filling & painting guide, but the problem i have is that the power is constantly on all the time to the unit, has to be switched off manually. (bound to get left on at some point and come back to the car with a flat battery)

i have tested all the terminals coming from the bypass lead(numerous times to double check), and i have 2 terminals on constantly but none pwers on / off when ignition turned.

Called the shop that ordered the bypass harness and he told me that it was normal to have t switch stereo's off manually, but if i really wanted it to work when ignition then i would have to go to the ignition barrell itself for a source as the seat heaters / TRC / SNOW power supply would not be strong enough an i would blow fuses, and i can't use the blower motor power supply as this will cause interferance with my sounds. i also tried the spare multiplug for the OEM head unit, and found no ignition wire on it either.

Is this a common prob with bypass lead???

Do all JVC units have to be switched off manually????

Where is the easiest place to tap into a power supply strong enough to power the head unit????

I wont be putting the unit back in for a couple of days till i've glued /filled & painted the modified fascia to the standards set by Wozza & others, so any response, idea's or methods used would be a bonus lads.

Cheers in advance,

Deckie.

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swap the perm and ign live on the JVC loom..

they 'should' be shrouded in clear plastic with connectors underneath

Thanks for reply redz and your right they are shrouded in plastic, but i can not swap them as the the bypass lead only has a permanent power feed (intended for the memory only), i have them both, Power and memory from the JVC loom looped into that one and only power supply as the lead does not carry a ignition feed.

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i have it connected it to cig lighter.

Thanks for quick reply Asi, but maybe our cars are slightly diferent, but my cigarette lighter works both when my ignition is on or off, this did come to mind but it would just provide me with another permanent feed. Thanks again tho!

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i have it connected it to cig lighter.

Thanks for quick reply Asi, but maybe our cars are slightly diferent, but my cigarette lighter works both when my ignition is on or off, this did come to mind but it would just provide me with another permanent feed. Thanks again tho!

drop the steering coweling off(few screws)and test the wires on the back of the ignition switch.you'll find a ignition live their.

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It does sound probably like a poor amp bypass lead. I certainly don't have the same problem with my own Pioneer head unit and an amp bypass lead. I would consider returning the amp bypass lead to the shop and asking for a refund since it doesn't work properly, and getting another one from somewhere else (e.g. eBay).

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i have it connected it to cig lighter.

Thanks for quick reply Asi, but maybe our cars are slightly diferent, but my cigarette lighter works both when my ignition is on or off, this did come to mind but it would just provide me with another permanent feed. Thanks again tho!

drop the steering coweling off(few screws)and test the wires on the back of the ignition switch.you'll find a ignition live their.

I never actually looked to see it was that easy to get to the ignition barrel, i thought there would be mre t cme off and was worried that clip's would break or end up with rattles, if its that simple thats the way i'll go, dont want to send back lead and wait for a new one, it will be getting fitted tomrrow.

Thanks again

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take the ign feed of the orignal loom then.. its in there and what it should be used for..

I wish i could!!!!

Thats the problem i've been having, checked all the wires that went to the original stereo, there are 2 power wires, both are permenant feed, the power stays to both wires even when ignition is off, i know this problem sounds thick, i know the original stereo switched off when ignition was off, and i sense the fustration in your reply, I nearly turned my head inside out trying to figure why i couln't find the ignition feed, but this is the reason i'm having to look for somewhere else to tap into another ignition feed.

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This is the wiring diagram for your OEM head unit/amp (assuming a Sport since that's what your profile says).

According to that, if I'm reading it correctly (redz, do you agree ?) then there were two black wires coming from the amp to the OEM head unit, and one of them (the one going into pin 10) is the switched live (the other being for a speaker feed to the amp). That used to be connected to pin 10 of the connector on the amp leading to the head unit, so your amp bypass cable should be picking up this same feed and passing it to the head unit.

Edit - ok, this has confused me slightly, but it looks like on the later cars (2001 on) the switched live feed was pin 11 on the OEM head unit, diagram here, and doesn't come from the amp itself. It is a grey wire on these later cars according to that diagram.

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i cant use that version of the wiring diagram as im on my mac but will check tomorrow on my pc.

that does sound right stevie..

ihave to say that if the old HU worked fine then the ign live was working fine..

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Allright boy's, got my head round whats up today and got the unit fitted and performing properly,

Your right Stevie, the ignition cable is the grey one on the plug for the lexus amp.

My Auto leads bypass cable has 2 yellow memory wires on seperate pins at the amp end, but they join together (both wires in same pin) at the head unit end...Strange.

Sorry Lad's, I was being a fud and looking a ignition feed on the multi-plug that went straight into the lexus head unit, i couldn't find because it wasn't there, obviously just perm feede ones there for memory, and then i discovered the grey wire down at the amp plug, scotch-locked into that feed and problem solved, I suppose Autoleads had a faulty batch of leads, let the guy at the shop where i got it fromknow, just incase he has to get another one for someone else, thankless prick couldn't care less!!!

Anyway, thanks again for your thought's, and taking the time to reply,

Much appreciated!!!!

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Thanks Stevie, I'm chuffed to bits with it, starting to look for something else to mod!! gets addictive!! i'm thinking speakers as the Lex ones cant handle the new sounds.

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