Looking for switched power source.

worstdayever · Nov 6, 2016

Edited for clarification: I have a bike alarm that im trying to install. It has pos and neg leads that connect directly to the battery. There is also a 3rd wire that needs to be spliced to an ignition switched power source(a wire that is normally cold until the key is turned then becomes hot). This wire tells the alarm that the key is in the ignition and not being stolen. My ignition is a 2 position(on/off) and there are 3 vertical terminals on the back.

Thank you!

Rohan · Nov 7, 2016

Not entirely sure what you are expecting, but don't forget that, stock, Commando's have a positive earth electrical system.
So a constant +ve 12v source will be available, switched, off the back of the ignition switch.

Some Commandos also have a power source off a 2 pin socket, near below your knee on the rhs, on 850 bikes anyway.
hth

kommando · Nov 7, 2016

You need to add one, if you have the 2 pin accessory socket its not switched and I used it for overnight charging before upgrading to 3 phase alternator.

worstdayever · Nov 7, 2016

Thanks for the replies! I have a small bike alarm that requires a switched power source(turns on when you turn the key). But every wire i check is hot. Or the back of the ign switch, i pulled all but the power wire from it and checked the spades with the key turned on and off. They were hot until i plugged the wires back in, then they were cold. I feel like im mssing something because of the whole pos ground thing.

comnoz · Nov 7, 2016

worstdayever said:
Thanks for the replies! I have a small bike alarm that requires a switched power source(turns on when you turn the key). But every wire i check is hot. Or the back of the ign switch, i pulled all but the power wire from it and checked the spades with the key turned on and off. They were hot until i plugged the wires back in, then they were cold. I feel like im mssing something because of the whole pos ground thing.

Check it with a test light -instead of a VOM. Jim

lcrken · Nov 7, 2016

It sounds like you are measuring with a voltmeter and clipping the common lead to ground, and then measuring with the positive probe. With a positive ground system, you need to clip the positive probe to ground, and measure at the terminals with the negative probe. Or, as Jim has suggested, use something like a test light that isn't polarity sensitive.

Ken

worstdayever · Nov 7, 2016

The alarm itself comes with a special splice connector that ive been using. When theres power, the power light comes on on the alarm itself. So iv been splicing into wiires i thought would be hot when the key was turned.

Danno · Nov 7, 2016

The tail light circuit would be the one to splice onto. It comes on with the key on or in the "Park" position. And there's really low load normally with only one filament.

Interbak · Nov 7, 2016

I just had a quick look at the wiring diagram for your '72. The white wire in your harness, which goes to multiple places, should only be hot when the ignition switch is in the ON position. As noted earlier, your bike has a positive ground system, so the + 12 volt wire on your alarm connects to the frame and the - wire (which would typically be ground on modern negative ground vehicles) goes to the hot white wire. If you don't have a shop manual with a wiring diagram you can find it right here on this forum, in this thread anybody-got-wiring-diagram-t3672.html
Don't hook your alarm up with with the negative to ground and the hot to "power" like your instructions likely say, you'll fry it!

Hope this helps, Brian

L.A.B. · Nov 7, 2016

worstdayever said:
The alarm itself comes with a special splice connector that ive been using. When theres power, the power light comes on on the alarm itself. So iv been splicing into wiires i thought would be hot when the key was turned.

"When the key was turned" is all rather meaningless.
Turned....to where?

I can only assume you mean you need a power feed for the alarm when the ignition key is at the OFF position, in which case the only 'hot' wire at OFF is the battery feed (-) to the master switch which is normally the brown/blue ('71on) connected to switch terminal 1, so with the key at OFF, there isn't a 'switched' power supply.

Edit: Correction. The 'Parking' lights wiring or terminal 3 of the switch can't be used to power the alarm without an additional isolating switch, as the tail, instruments and pilot lamp (if fitted) will also be switched on at 'Park' and the alarm would be powered up when the lights were on (key at 'Ignition and lights').

worstdayever · Nov 7, 2016

So youre telling me you just go out to your car/truck/bike and hit the gas and go? Or do you use that meaningless key to give power to certain components to be able to start the vehicle? The key position is giving no power in the off position and giving power in the on position. Your assumption is wrong. The alarm is wired directly to the battery but needs to be wired to a component that is only on when the bike is on.

L.A.B. said:
worstdayever said:

The alarm itself comes with a special splice connector that ive been using. When theres power, the power light comes on on the alarm itself. So iv been splicing into wiires i thought would be hot when the key was turned.

Click to expand...

"When the key was turned" is all rather meaningless.
Turned....to where?

I can only assume you mean you need a power feed for the alarm when the ignition key is at the OFF position, in which case the only 'hot' wire at OFF is the battery feed (-) to the master switch which is normally the brown/blue ('71on) connected to switch terminal 1, so with the key at OFF, there isn't a 'switched' power supply.

Edit: Correction. The 'Parking' lights wiring or terminal 3 of the switch can't be used to power the alarm without an additional isolating switch, as the tail, instruments and pilot lamp (if fitted) will also be switched on at 'Park' and the alarm would be powered up when the lights were on (key at 'Ignition and lights').

Torontonian · Nov 7, 2016

Alarm ! Wire it fused into battery . Park it under lights and believe it or not in a place with lots of people. Research who steals what , and you will find most stolen bikes are brand new squids. The best new alarms come with a belt clip chirper when some jerk dicks with your machine. Then you get to ditch whatever it is you are doing and investigate a mom bouncing her new baby up and down on your gas tank.

worstdayever · Nov 7, 2016

Torontonian said:
Alarm ! Wire it fused into battery . Park it under lights and believe it or not in a place with lots of people. Research who steals what , and you will find most stolen bikes are brand new squids. The best new alarms come with a belt clip chirper when some jerk dicks with your machine. Then you get to ditch whatever it is you are doing and investigate a mom bouncing her new baby up and down on your gas tank.

Haha a friend of mines hd sportster just got taken from in front of his apartment. I live in san diego so things end up on the other side of the border real quick.

L.A.B. · Nov 7, 2016

worstdayever said:
The alarm is wired directly to the battery but needs to be wired to a component that is only on when the bike is on.

Well, it would have helped considerably if you had said that at the beginning, then those of us who are trying to HELP YOU wouldn't have had to make assumptions and attempt to make 'electrical sense' out of what you said about not being able to find a switched power source. :?

L.A.B. · Nov 8, 2016

worstdayever said:
Edited for clarification: I have a bike alarm that im trying to install. It has pos and neg leads that connect directly to the battery. There is also a 3rd wire that needs to be spliced to an ignition switched power source(a wire that is normally cold until the key is turned then becomes hot). This wire tells the alarm that the key is in the ignition and not being stolen. My ignition is a 2 position(on/off) and there are 3 vertical terminals on the back.

Ok, that would appear to be the pre-'71 electrical system as it has a 2-position switch unless the electrical system has been modified in some way (as your "1972 Fastback" would normally have a different wiring layout with a 4-position switch) ?

So, with the switch 'on', white is the switched power supply and therefore 'hot' at all times but it's 'negative' so the polarity might not be correct for the 3rd wire connection if the alarm is designed for negative ground.

Looking for switched power source.

worstdayever

Rohan

kommando

worstdayever

comnoz

lcrken

worstdayever

Danno

Interbak

L.A.B.

Moderator

worstdayever

Torontonian

worstdayever

L.A.B.

Moderator

L.A.B.

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