Finding a Fuse Triggered by Ignition

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Peacefield

Member
I have a 2008 and I'm trying to hardwire my radar detector. Either I don't understand how to read the "map" or I'm not understanding something correctly. I've attempted to connect the RD's hot lead to a fuse for something that does NOT work when the ignition is off. The map indicates three fuses for the radio. Yet, when I connect to any one of the three, the RD turns on with the key off. I tried hooking into the fuse for the power windows and the same thing.

What must I be doing wrong?
 
Hmmm.. some items on the car stay on with the ignition but sleep a while after you've locked it, so maybe it's not as simple as cutting the power to those devices with the ignition off.

for example - with the ignition off my roof / windows won't work, but then I can hold the unlock button on my key and both will work, so I doubt the power is restored then the motors told to operate.

My RD is wired by having a second Cigar Lighter socket behind the dash - much easier to remove without cutting any wires, works perfectly with the ignition / sleep.

Good luck & let us know what you do !
 
From someone who has a RD hard wired... Just put it on a hot lead and turn the detector off when you park. Besides, you shouldn't leave your detector in view when you park anyway. I remove mine when I'm in a public place and just turn the RD off when in my garage... to my best knowledge, there are NO leads that are connected to the ignition on the Z4.
 
Thanks, guys.

I know it's possible as I had this same detector mounted in the 2004 I just sold to buy the 2008. If only I noted which one it was connected to, but I wouldn't have expected this to be the challenge it's become. I like having it on/off with the ignition so that I never have to worry about forgetting to turn it off and draining the battery. And I've always left it in the car. The way it's mounted and the wire routed, it's nearly invisible from the outside with the top up.

I'm doing this work with the driver's door closed and the key out of the ignition. As soon as I pop in the fuse, the RD turns right on. A mystery.
 
If you tied it into the same feed as the radio it would go on/off with it .

I'm not sure of the load in an RD but it can't be much.
 
Mine works exactly as you require above and I'm very happy with it.

It's pretty easy to remove the roof control / heated seats console switch thingy (I love making up new names) and grab the feed for the cigarette lighter.. run it under the panel under the heater controls which also removes easily.. job done :thumbsup:
 
Either the red or yellow cable running to the radio's iso connector will be a switched accessory feed. You'll really need a multimeter to check though.

Check the pinouts on this page... Youre looking for Pin7 on Connector B :) http://www.isham-research.co.uk/quattro/wiring/Typ85/isopin.html
 
Thanks, everyone. Ed, I appreciate that link, but I don't have a meter and this seems a bit beyond my ability (my level of understanding doesn;t go much beyond sticking a wire in with a fuse) :roll:

It is getting frustrating, though, they ALL seem to be hot. I've tried the fuse for the a/c, the heated seats, the radio, the window, and so on. All working while the driver's door remains shut and key out of the ignition. I can't figure out how this could even be.
 
Its because they're all on Relays (or similar Transistors/Switch modules) Peacefield :)

For example, the [Battery - Fuse - Switch - Heated Seat elements] are not a single circuit. The relay for the heated seats will always have a +12v battery feed ready, but the heated seat switch will be on a separate circuit that IS controlled by the ignitions 'accessory switch'. This prevents having to put high-current wires all throughout the car :)

All the relays are behind the fuse panel.

Therefore i suggest you go for one of the high current, switched feeds which will be either the Radio one (as above) or the cigarette lighter socket (make sure it does turn off though as ive never used mine!)
 
I tapped mine into the back of my ciggy socket - but then realised it is always on, so my roadangel is on even when my car is off :headbang:
Coming from jap cars never had this problem before!

The other place is the purple and green wire inside the vanity light - which powers the autodimming mirror - which people who fit the valentine 1 use - which i plan to do this weekend if its dry - so i can lower the roof and remove the A pillar - before i flatten my battery with my ciggy power!
 
EdButler said:
Its because they're all on Relays (or similar Transistors/Switch modules) Peacefield :)

For example, the [Battery - Fuse - Switch - Heated Seat elements] are not a single circuit. The relay for the heated seats will always have a +12v battery feed ready, but the heated seat switch will be on a separate circuit that IS controlled by the ignitions 'accessory switch'. This prevents having to put high-current wires all throughout the car :)

All the relays are behind the fuse panel.

Therefore i suggest you go for one of the high current, switched feeds which will be either the Radio one (as above) or the cigarette lighter socket (make sure it does turn off though as ive never used mine!)
Click to expand...

Ah, that's a real eye-opener. Being the neophyte that I am, I want to make sure I'm interpreting this correctly. I want to remove the fuse panel, find the radio relay panel behind it, and according to your earliier link, find Pin 7 - ignition - +12v input to the radio when the ignition is on. ?

Is this difficult or fairly easy for someone with some basic mechanical but little electrical skill?
 
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