AE102 wiring easter-egg hunt - finding ACC/IGN switched +12V in rear of car

[Hiro]

Ok, so long story short I was wiring up my subs and amp over the weeked, and in my frustrations over trying to get the power lead past the firewall (fixed, but painful), I neglected to run a remote-sensing wire to hook up to the head-deck. Now, unless I really have to, I'd prefer not to have to rip the console apart again and pull up the door sills to run just one measly wire to the head-deck, so I had an idea.

What would be the best source of either ACC- or IGN-switched +12V in the rear half of the car? Not too concerned about which one, as I'd be unlikely to have the subs running on ACC much. Car does not have a rear wiper, power windows or other electrical features that might be tappable, but I do have full wiring diagrams for it - my first (and so far only) idea was the fuel pump, which is conveniently located under the rear seat and takes 10 seconds to get to. Comments on this choice/offer another alternative option please.

[Cuzzo]

Just do it from the headunit.

The amp will still be on if you turn your headunit off.
Might not be a problem but im sure it was designed like this for a reason.

[oldcorollas]

fuel pump will be off when engine is not running

fuel level sender will have power from dash when IGN is on, but will affect the reading

best bet for IGN would be one of the junction boxes in the kick panels int he front? ie, from EFI/main relay etc

bt yeah, as Cuzzo said, better to do it right first time

[Hiro]

I'm not concerned about the subs not running when the car isn't (I don't sit in carparks pumping fully-sik tunes), nor am I worried about the amp still being on when the headunit is off, as long as it turns off when the car does so it doesn't run the battery flat.

[Cuzzo]

Setup a relay? Run two wires. One from battery and one from the ignition?

No but seriously just run it correctly. If you want to do bodgey stuff, use one of the RCA leads as the remote wire and split the other rca to a Y cable for your both inputs on the amp.

??????

Profit

[Hiro]

Not really sure why everyone's jumping on the "it's bodgy, do it properly" bandwagon, the remote sensing wire only draws minimal amounts of current (like 0.5A) as it is only being used as a trigger to tell the amp that the ignition is turned on, so I'm not seeing a problem with tapping any old 12V source for it - not like it's a 0 gauge power lead drawing 30A at full noise.

It'll probably only be a temporary thing anyway as I'm lining up a new head-deck in near future, and I'd run it properly then (quite likely going to amp my speakers then too so would need to run new RCAs anyway, plus a distro block for the power)

[oldcorollas]

well there isn't any 12V IG or AC switched power in the back of the car anyway?
should be able to get something from the kickpanels at least.

it's not bodgy, but it makes it easier in 12 months when you put new deck in and go "what the heck is that wire" heh heh

[Hiro]

well there isn't any 12V IG or AC switched power in the back of the car anyway?
should be able to get something from the kickpanels at least.

it's not bodgy, but it makes it easier in 12 months when you put new deck in and go "what the heck is that wire" heh heh

New head-deck is more like 1 month rather than 12 months away, which is why I'm trying to limit the number of times I have to pull the dash apart (each time seems to result in one less screw or one more cracked bracket, along with 2 or 3 stabbed/cut/bruised hands....stupid big hands)

[oldcorollas]

if you hooked it into the brake lights, you would have fooly sik bass as you pull up to lights


hmm... handbrake wire? thats IGN.. your dash light might glow a bit tho..

[Hiro]

if you hooked it into the brake lights, you would have fooly sik bass as you pull up to lights


hmm... handbrake wire? thats IGN.. your dash light might glow a bit tho..

Brake lights aren't ignition-switched though
And handbrake is far enough forward that other options would be available (but also requires more trim to remove)

As mentioned before, fuel pump gives the best compromise of a) least amount of stuff to remove (rear seat base just lifts out, and wire can feed straight into the boot under the back seat), b) switched mode (only when engine is running, which prevents battery drain) and c) location (only need about 80cm of wire or so)

[dfunkt]

would hooking it up to the licence plate bulb interest you, or does it have to be ACC?

sure it would mean you have to turn your parkers on to turn the amp on, but since i drive with my lights on almost everytime anyway, i've done it this way in the crown.

[LeeRoy]

For the time it would take to hook it up off something in the rear you might as well do it properly and run it off the head unit.

I agree it's a pain in the ass but it's seriously a 1hr max job.

[TERRA Operative]

Do your RCA's have an integrated third wire? Some do that make a good remote on wire.

[Hiro]

Do your RCA's have an integrated third wire? Some do that make a good remote on wire.

Nope.
Even if they did I'd still have to pull the dash apart to get the head-unit out, so it's really only cutting one of the steps out.

Will probably just suck it up and rip the trim out on the weekend, at the moment I've got the remote hooked up to the power line, and just pull the RCAs out when I lock the car (otherwise the subs have a nice "hum" that drains the battery)