Is it possible to add a motion sensor to a stock honda alarm? Anyone got schematics if possible?

 

My apologies if this sounds more complicated than it's worth.

This should be possible. The simplist way I can think of would be to use the 'ground' ouput of the motion sensor (most sensors have this) to activate the 'door switch' input on the Security Control Unit.

The only tricky part is to make sure the input on the Security Control Unit does not draw more current than your sensor can supply. If it does, toasted sensor, but I doubt it would be a problem. This is usually only a problem if the connection point you choose also powers the interior or dash lights. The connection point I am recommending to you only goes to the Security Control Unit and the Keyless Door Lock Unit, nowhere else, so should not have this problem.

If you have a meter, you can test to see how much current it takes to trip the door switch input, (hopefully less than 100 ma) if you don't you can use a plain cheap LED to test it. That way, if it's not compatible, you'll fry the $.50 LED instead of your sensor.

You can try this test if you want:
(I would do this myself and report back to you, but I don't have the factory alarm)

Buy a regular old LED. Make sure it's NOT one made for 12 volt use, those have built-in resistors. Just a regular 'ole LED.

Locate the blk/wht wire on the Security Control Unit (under the seat). It's wire #2, which is between an empty wire hole and a blu/blk wire. It's the only blk/wht wire on the connector.

Connect a wire to this blk/wht wire (don't cut it), arm the system, then 'ground' the wire. The alarm should trip, just as if you opened a door. Reset it.

Arm it again, and this time, put the LED in series with the wire and ground, so the 'ground' goes through the LED. One direction it won't light up, the other way it will. If it lights up, the alarm should trip.

The real test is if the LED does not fry. If you can leave it connected and lit up for a few minutes, all is OK. If it comes on real bright, then quits and won't light again, we know the Security Control Unit draws too much current.

If the LED lives, you can connect your sensor's 'ground output' wire to the blk/wht wire. If the LED dies, let tme know, you can still do it but you'll need a relay.

 

Modifry, Thanks for all the info!! I'll give it a try.

 

Timeless, let us know how Modifry's suggestion works out. If it works, I'd like to add that capability on my stock alarm as well.

Thanks,

cal

 

There was a thread a while back of how someone connected his radar sensor to the hood switch input. It worked.

 

modifry, any comments re the approach CHOWBOX mentions?

cal

 

Should work. Basically, any input that uses a ground to trip the alarm should be usable.