Anyone here understand neutral switching?

I'm just about done wiring-up four devices to four toggles in my Euro Parcel Shelf: PIAA 1100 Driving Lights, UNIChip A/B map, additional interior accent light, AND a sonic deer avoidance unit (Hornet XP3).

It is the last one that is wired via neutral switching - where neither of the two wires to the toggle carries positive current.

My billet aluminum toggles (match the interior very well I might add) have a built-in LEDs at the tip of the toggle. I like the reminder of knowing of what I have activated. For the previous three items, when they are turned-on, the LED lights.

The XP3 comes with its own toggle, and the unit works just fine. I added a ground wire from under the dash, and changed to my toggle of choice, and the best I get is the light being on, but when the device is off. When turned-on, the LED goes off. I want the opposite...

The seemingly simple wire diagram can be found here:

http://www.xp3hornet.com/mount.shtml

I'm thinking that if I replace one of the two neutral wires with a hot one, that might do the trick. I just don't want to damage anything though...

Ideas are very welcome! Thank you.

 

I had a hard time with that too...I'm no electrical expert and ended up by trial and error with test leads that had fuses attached to find out

 

So you also have a light on yours? With the provided toggle, the two wires can go to any prong on the toggle and it works fine... Did you end-up running power to the toggle? Thanks for chiming-in!

 

I didn't follow instructions:smile: I attached one wire to a power on lead (park lamp as I only use it in that mode) and the other to ground. When I hooked it up to a lit switch, that's when the fun began. The first time I tried, I smoked the wires SHORT AAAAHHHHH!!!! I should restate my electrical competance...I'm an idiot when it comes to electricity Don't ask me how, but I managed to figure it out with the safety of fused test leads the following round so I could find the correct connections without my Mini going up in flames God...save me from myself

 

Well, you just confirmed that I should indeed be a bit leary about playing with the wire connections alright! I thought you went with a toggle so you could over-ride that high pitched noise...

I too am not as knowledeable as I would like to be regarding such stuff... I think GBMINI and Greatbear ought to know! I'll try contacting them

 

What is the wiring to your toggles? Are there only two connections? I think there should be a third - 12V from battery, switched 12V to thing being switched, and 0V for the LED. Correct?

The problem is you will need to modify inside the switch if it is truly an LED indicator - because LEDs only light with current in one direction. If it is a small bulb, you would be OK to modify externally.

Honestly, the simplest way might be just to wire the whistle so that the switch does carry 12V+. Change so the feed after the 1amp fuse goes down to the switch, through it, and back then continues on the original wire to the whistle, and the other wire from the whistle which at present goes to the switch will now go to battery negative (chassis).
That way, your toggle switch LED will work exactly as intended.

 

Tony, I am using a toggle/led switch. The part of the switch that confuses me is the labeling. There should be three prongs at the bottom of the led switch...ground, lead, power. The lead and power is what screws me up. Is the lead meant to be the constant power source or the power Anyway...hook it up wrong and it'll either not light the led and/or short your ground The ground is easy so you have 50/50 chance of getting it right/wrong

I soldered a couple of aligator clips to a test wire with a 20amp fuse in the middle. Make two of these and then try it. The fuse will blow if you get it wrong

 

It sounds to me like what they are calling "neutral switching" is actually ground switching. In other words, rather than switching the +12V line in front of the load (device) they are switching the ground line behind the device. I have no idea why they would want to do that other than for convenience sake (no need to find a +12V source inside the car, just run the wire to any grounded metal surface).

Lots of cars these days switch the negative (i.e. ground side) side of a circuit instead of the positive side.

I _think_ this is what they are talking about. I could be wrong.

 

Pete,

You are correct and probably the correct reasoning too ... in theory the shorter the 12V+ side of the wiring, the less chance of a short. In practice, so long as the fuse is close to the battery, any short will blow the fuse and not cause drastic damage.
But most electronic controls (for example the BC1 which controls all MINI lights, wipers, etc) switch the 12V+ side, then the other side of the device is just wired to chassis (12V-).

 

Guys, first THANK YOU! GBMINI, I truly appreciate the response to my PM over the night...

Let me first try to address a couple of questions. The wiring provided to the toggles WAS just those two wires, as in the diagram. When that was not working with my LED toggle, I did add a ground wire as well, making for 3. And as I shared, the toggle would only light when off...

Oh, after checking my work voice mails last night (on "vacation" now), I got a message from Otto at XP3. I'm currently waiting for him to ring me back. But he did indeed share that "neutral switching" is actually ground switching. Bingo Pete! And he said that a relay would do the trick?! I hope to get the details when he calls a bit later...

And yes, I do believe "this" was indeed done for convenience purposes, I think to avoid the need to ground the unit directly to chassis ground...

The LEDs at the tips of these toggles are quite small, I'd say a 1/16" in diameter...

If need be, I suppose I can re-wire it as GBMINI mentions... MSFITOY, I like your fuse idea! Sounds like a safe way to experiment...

A relay though? Can anyone guess how a relay can "fix" this? Thanks again.

 

hmmm....I don't have a relay attached and everything is working. Let me back track as to how mine is set up Tony. The first time I hooked it up, I simply spliced the "switched +" line going into the driver's side park lamp (parallel hook up). That way, when those lamps are on, the Hornet is also on (sharing the lamps power). As I drive with the park lamps on day and night, I wanted to be able to override the power to the Hornet during the day time. So I extended the two lines tapped into the lamps through the firewall and connected them to an internal LED switch purchased at Radio Shack (three prong). The Hornet seems to draw little current as to not affect the output of the lamps, hence, no need for relay or seperate power source.

 

Thanks MSFITOY. That is very clear. When I mentioned relay to my dad, his first response was - how much current is thing drawing? It's minimal: 10Ma (max) at 12 VDC. So, I don't get the relay solution. I haven't heard back yet. I'll try calling again...

 

A picture:





The top pic shows how the switch is supposed to be used. When the switch is closed, the 12V coming in goes out and also goes to the LED; the third wire gives 0V (ground) to the LED so it lights.
The bottom pic shows what you have.
When the switch is open, the LED is connected to the device - but the device is connected to 12V and so the LED (which needs very little current) can steal enough current through the device so it lights. Thus you have the LED on when switch is off.

If you don't want to change the wiring as I suggested above, then a relay can be used:
You wire the switch as in the top pic. But the (12V) output of the switch goes to the relay instead of going straight to the device. The other coil connection of the relay goes to 0V. Now the relay will be closed when the switch is closed and open when the switch is open.
Now you use the two switch contacts of the relay to control the device.
Important: you need a reverse diode on the relay, otherwise you will burn out the switch.

Your Dad is correct (of course!) the current draw is minimal and a relay is a bit of a waste.


(PS: you would think I would draw with some fancy computer program wouldn't you ... but that took seconds instead of minutes!)

 

That's what I figured...it's the way the manufacturer of the switches label their product is what screwed me up

 

I'm just having a chance now to get this done... First, thanks for the additonal comments, and pics! I have decided to re-wire this guy...

The basic concept is well-understood, I believe:

12 volts into "power" of toggle
12 volvs out of toggle "acc"
chassis ground wire to "ground" on toggle

Now, what needs to happen here...



I should be able to tie-in the two wires above that go to the battery (+ & -) and take this to the "acc" on the toggle. 12v swithced power is already going into the toggles "power" prong. And I ran a ground from under the dash to the "ground" on the toggle switch...

This leaves one of the original toggle wires without a home... Should this work? It seems that it would. I'll wait an hour or so to get an opinion before I give this a try...

Thanks much!

 

Yes...that will work. You have the newer version with plugs...cool

 

The wire that goes from battery + to fuse now goes to "power" of toggle, or is scrapped if you have fused power already at the toggle.
The wire from the other side of fuse (where it says "1 AMP") goes to "acc" of toggle.
The wire which originally went from "weather tight connector" to "switch" now needs to go to ground - at the toggle switch, at the battery or anywhere on chassis.
The "spare" original toggle wire is the one that was coming from battery - and is now scrapped.

Should work perfectly

 

Thanks for the confirmation, and clarification! I have about 30 minutes of daylight left... I'll let you know how it went!

 

Well, I never got out there until after 9 pm PT, but after about 10 minutes of stripping and twisting a few wires, it works!!! I'll do a nice job of it later tomorrow or Friday...

All, and especially to GBMINI for the trip over here, thanks much for the knowledge.

 

Fabulous - well done!

No problem - enjoyed the discussion :smile:

 

And what about those lighted billet toggles? Any pics or sources? It would be nice to have a source for a part that goes well with the other instrumentation.

Steve

 

I have a better photo somewhere, but this should give you an idea:



Red = Hornet XP3 (deer sonic device)
Green = UNIChip, B map
Blue = Interior blue beehive light

I have another blue led toggle on the other side of the parcel shelf for the PIAA DLs...



http://maxima.cardomain.com/item/PILPLSW1