Alarm door lock/unlock wiring.

[[ion] C2]

It's been a while. Got a new alarm I'm trying to make work the keyless entry. I know our cars use a negative only lock/unlock system and one negative pulse has to go through a 1500 ohm resistor.

But what do I do when the outputs for lock/unlock are like this?

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[a.graham52]

Ask the manufacturer.

[[ion] C2]

I think I need to use diodes so I can use both the blue and green wires and make them only output negative.

[guiguilandry]

IIRC I used 2 relay to switch the current on mine... but it's been like 6 years since..

[[ion] C2]

I e-mailed the manufacturer.

Your car has a Type H negative multiplexed doorlock system. In order to connect an aftermarket system to control the locks you require relays and resistors.

I looked up that style and got a nice little wiring diagram.

[guiguilandry]

yep there ya go... this is exactely what we did on mine

[[ion] C2]

The only thing I don't get is that one wire on the alarm is "- unlock, + lock" and the other wire is "+ unlock, - lock" ....

So let's say if I just run the blue wire to a relay, and the other end of the relay is connected to constant +12V... when I hit the button to unlock, the relay will function. What happens when I hit the button to lock and the alarm sends a + pulse to the relay?


Like... is this how you do it?

[guiguilandry]

It's been like 6 years since we installed it and I wasn't the one doing the wiring... but I remember one thing and it was that my alarm/remote starter was sending positive pulse for lock and unlock and that we had to use relay to switch it to negative..

I do not remember at all about the resistor part, but I'm sure you can figure that out...

I made a little wiring of what we did to switch pos+ to neg-

[[ion] C2]

Yeah I mean it makes sense using relays. I'm just wondering how the whole "lock negative, unlock positive" goes using the same wire... like if I hook things up the way I made my markup above, will it catch on fire when the wrong polarity pulse comes through? haha