Over the weekend, I wired up my PIAA540 driving lights. It turned out real
nice. Anyway, I tapped the trigger switched wire to my iginition so that I can
turn the lights on while the car is in the ON position.

I was originally planning to tap into the cigarette lighter fuse... only to
find out that there is some electricity running through there while the car
is off.

I thought my head was playing games on me because my radar detector is
off while the car is off. Just for the heck of it, I turned the car to the ON
position and watched while the radar detector turn on...I pulled the fuse out
and watched the radar detector turned off (duh)... I shut the car off but
and there is still power going through the fuse. I did not take
a meter on it because my alternative was to just tap to a different fuse.


This is very weird...my other cars have no power running through the
cigarette lighter while the car is off. Is this normal?

 

Yeah, that is strange.

Maybe the socket power isn't controlled by a mechanical relay -- could be a solid state switch if you're seeing "power" (I assume you mean some positive voltage).

However, it's unlikely that the socket will supply much actual power (ie, current at some voltage) when the ignition is off, even if it is a solid state switch.

So hooking up your driving lights should be OK and they should work the way you want them to. That should be easy enough to test with a temporary hookup before you commit to a more permanent wiring change.

 

Yah, this is weird... there is enough (+) power running through the
cigarette lighter fuse while the car is OFF to send enough juice to the
PIAA on/off switch with LED to latch on the 540's while the car
was off. hummm...

but anyways, I have it wired up to the iginition fuse so Im ok. 540's
do not turn on while the car is OFF.

 

In the case of the cig lighter power, the fuse is in the circuit ahead of the relay/switch which controls the power to the socket. Many of the circuits in the MINI are wired like this. This is sound electrical design; if the circuit was fused after the switch, any sort of shorting-type failure of the switch would not be fused and would cause damage to the electrical system (or take out a fuse link which feeds several other accessories, shutting them down as well).

 

All of the vehicles I have wired (which is quite a few) have had power to the power outlet in the "off" position. This is why I always wire my CB to that.

 

Well, as kenchan pointed out, if you plug in a radar detector, it will turn off when the ignition is turned off. Obviously, if the socket was always hot, the detector would stay on.

Not quite sure why they wouldn't turn the outlet completely off unless they're allowing for on-demand power use (ie, full power turns on when needed) for an actual cigarette lighter. But then, why have all the design complexity -- just leave the socket powered all the time. Of course, these are the people who brought us iDrive... Who knows!

Now I'm curious -- I'll have to find the lighter to do a test...

 

I have noticed that Chrysler / Jeep, Suzuki, and MINI switch the Cigarette lighter off when the car is off. The rest are on all the time, which allows you to use a trouble light, or air pump or other accessory when the car is off.

The procedure to protect the car radios memory when working on the car used to be to plug a charger into the cigarette lighter and leave the car off. I used to charge car batteries through the cigarette lighter with the car off.

Some cars now have two "cigarette lighters" one marked with a key, and one marked with a battery. The key one works with the key.

As for the Radar detector, and many Cell phones. When the car is off there is 12.6 volts on the accessory socket. When the car is on, there is about 13.8 volts on the accessory plug. It does not take much electronics to automatically switch the equipment on and off based on sensing the voltage. Many car alarms work by doing just that. The door opens, the dome light goes on and the alarm senses the change.

John

 

My experiences have all been with Jeeps. I would tend to agree that the voltage difference is sensed by the radar dectector, though. My power inverter powers off when the vehicle is turned off, however the CB will stay on.

 

I don't know about everyone, but I think Greatbear is correct...
that the relay for the cigarette lighter socket is after the fuse box.


The radar detector running a 3-5v circuit will probably still turn on even if
the battery is too dead to start the car... meaning, it will turn on probably
at even 9-10v. Im not certain, but just a guess. :smile:

 

I taped my 540 relay to one of my running/parking lights. The relay will sense power when you have the running lights on. This set up allows you to run the 540s with or without a key, parking, lowbeam and highbeam.

You could also tap in the green wire w/black stripe on the back of your OBD port. This is a switched 12v power source tied to the key/igniton. I used it to power my hardwired radar detector. It has zero voltage with the ignition off. Test with a volt meter to verify on your car, mine is a 02/03 build.

Be seeing you!

 

Ok, this bit me too. After searching, I found this thread which is my current problem.

I am trying to get an ignition sense from the fuse box. I am taking an always on power from the horn. I was trying to sense the ignition for my cell phone car kit from the ligther. It wasn't working, and I now understand why from this thread.

So, is there a place where I can sense the ignition from the fuse box? I am trying to do this with fuse tap type spades, and to not dissasemble the console, or splice wires.

PS. Where the heck did this electrical modification forum come from?

Thanks!

 

Ask and ye shall recieve! Mark and the gang are great. I had a bear of a time trying to sort out the electrical stuff from the rest, so I suggested a separate forum. Bada bing bada bang, here it is! They transferred relavent stuff from other forums to this one. EASIER SEARCHING!!!

I need all the help I can get, as I'm not a "natural" electrician.

 

I love the "Add-A-Circuit" option!

http://www.anythinggps.com/browsepro...--10-Pack.html

Right from the fuse panel, swithched or un-switched, you decide I think I'm running with three of these now. They make for very clean installs...

Just noticed that link is for a 10-pack... One can be had at your local auto parts store for 8 or so bucks...

 

Best way to add a circuit imo, is to run a 10 or 8 ga wire to the battery, put a 60A fuse on it, then run the wire to a terminal block where you need multiple circuits, then run off it, and pop a relay in line for circuits you want switched.

 

This is good idea but:

A 60A fuse should be fed with at least a 6 gauge wire. Both 10 and 8 are too small and will overheat if overloaded. 10 ga is good for 30 amps load, and I believe 8 gauge is rated for 40 amps. Also you should only continuously draw up to 80% of the fuse or circuit breaker rating. Any components you would wire into the terminal block with this arrangement should have individual fuses also, sized for the load involved.

 

"Best" vs. "Easiest."

I, for one, don't know anyhting abotu relays, or what type to tuse, for instance, of how they make things switched. Have photos? THe add-a Circut thing makes sense. That's about my level of wiring.

 

Bosch 12v 40 amp SPST is all you need! Relays use a magnet to pull a padle from the NC terminal to the NO terminal.


Tangent:

Relays, electromechanical switches.

NO - Normally Open (Connects to C when relay is energized)
NC - Normally Closed (Disconnects from C when relay is energized)
C - Common Terminal (Connected to NC when relay is not energized, connects to NO when relay is energized)
+ - Positive Terminal (Apply Power to this terminal to energize the relay)
- - Negative Terminal (Apply Ground to this Terminal)


Examples:

Ex.1 has no power to +, so relay is in its Normal State.
Ex.2 has power on +, so it is energized.

 

Thanks! That makes alot of sense to my mechanical brain, but if I were wiring in a new pannel from the battery terminal, wouldn't I have to wire the relay to a switch that would activate it to open/close the cicuit? That's where the whole thing starts to get fuzzy. I can certainly understand the need for digrams!

I think Haynes has a book on automotive electronics. I've beent hinking about buying one.

 

You wire the + to a wire thats only on with the ignition in ACC mode. and just tie the - to a ground (like a good bolt).

 

Stuck!

When I turn my ignition on, my deck powers on, but when i turn the ignition off, take the key out, get out of the car, lock the car, my deck still stays on!

What did I do wrong, I think its my accessory wire, I was using a add a circuit in the fuse box but maybe im using the wrong one?