negative relay, lock, unlock

Hi, need a little help in a relay problem.

I have fitted two extra deadlocks to my Dodge Sprinter van which require negative feeds on each side of the MES relay to lock/unlock.

I have searched for the wire colors and have tested a few in the rear cabin but no joy.I have fitted a Cobra alarm which does give a negative feed when armed,this is great for the locking of the extra locks and its independant of the factory central locking so in my mind is more secure.Trouble is, I need a seperate negative feed when disarmed/unlocked to the extra dealocks.

I'm  thinking, is it possible to wire a relay so I can feed it a negative signal and when the negative signal (from the alarm) is removed it gives a seperate negative feed to unlock?

TIA

Thanks for the reply...reason is,theres none!!

Its a can-bus alarm so it connects can high/lo to the wiring,theres only a steady - output on the alarm when armed,its then dormant when disarmed hence the need for a schematic.

How about hooking a relay to the unlock actuator of the front doors?

Pin 85 - +Unlock

Now, everytime the doors unlock a pulse will be sent to the added deadbolts.

Reverse polarity? Good idea ,thanks.That puts it back on the central locking circuit and could compromise security for the rear of the van if the locks are popped.

Also,finding a positive pulse on unlock may be tricky as these vehicles hate cutting into the electrics.

I found this https://www.the12volt.com/installbay/forum_posts.asp?tid=95063

I tapped into the yellow/white wire and it doesn't give a - output.

How about hooking a relay to the unlock actuator of the front doors?

Pin 85 - +Unlock

Now, everytime the doors unlock a pulse will be sent to the added deadbolts.

[QUOTE]

Thanks Kevin, I actually found a blue/black wire on the harness right where I needed it which gave 12v+ on unlock,wired it as you suggested and its perfect.One of the reasons I donated to this site as its members are so helpful :-)

On a side note, I have an ignition trigger wire which is low gauge and I want to use this to power several relays,is there a max draw for the trigger wire or would it be wise to connect the trigger wire to a relay to give me multiple trigger wires?

I was thinking of this

85- ground

86- ACC wire ign on

87- out to trigger wires

30- constant power

87a- No connection

Anyone please?

Could really do with a suggestion on wiring a relay that gives a negative output when a negative is removed,its too easy to pop a window the way its wired now and press the unlock switch on the dash.

TIA

Can it not be done?

Thanks