HiProfile

First off, this isn't exactly a guide how to put a main relay kill on any particular Honda. Just 2 different main relay kill methods via relays. The first is simple, the second is very secure.


Initially I put in a main relay kill on my EG by wiring the main relay's [coil/signal] ground wire (IIRC just the black wire) to my DEI alarm's armed output wire. I also relocated it FAR under the dashboard. For remote start, I put another relay in disable that relay when I activate the remote start. It's wired to interupt that relay's coil (kills the kill relay ), activated by the status output wire (supplies ground during entire remote start sequence).

However, I was facing some issues. One was a power-drain problem (not neccessarily related to the extra relays), the other was the alarm killing the main relay at weird times (30 seconds after disarming). I installed some ultra-low drain relays (11mA vs 125mA!), but had another idea...


The new way I intend to opperate this is by a single special relay. It will draw FAR less power, but also add more security. It's a latching relay (bistable), meaning you pulse it power to activate/deactivate it, instead of supplying it constant power. That leads to zero battery drain, unless you keep pulsing it. Using a latching relay with 2 coils, you can hook one coil to the factory disarm wire, and the other to the factory rearm wire. It will pulse the disarm wire to enable the main relay when it unlocks your doors or remote start is activated. Conversely it will pulse the rearm wire to disable the main relay when it locks your doors or the remote start shuts down. Now you have ZERO power drain from that relay.



The other good thing about this is the added security. With a regular relay, your main relay kill will "fail" if they remove the alarm brain. With a latching relay, they ALSO would have to rewire the main relay's ground. W/o a disarm pulse from the alarm brain, the main relay will remain "killed".

The other added security is the convenience of an easy main relay kill switch. Wire a momentary switch to your latching relay's rearm wire (use diodes just in case), and you can kill the main relay. This will make a permanent main relay kill until you hit the disarm button on your remote. Otherwise you'd need a second switch to pulse the disarm wire on the relay. So if you plan on leaving your car stored for a few days and worry about battery drain from the sensors, you could just lock the car manually and hit the kill switch. Even with a dead battery, the main relay remains dead until you arrive.

FYI you can do this with any subsystem you want in your car, such as a starter kill, headlight kill, etc. Just make sure you use a relay that can handle the power.


Relay links:

This is the ultra low-draw relay I used; it can handle 2 amps per "pole", meaning 4 amps if you bridge them:
http://search.digikey.com/scripts/Dk...name=PB1058-ND

This is the latching relay I intend to use for the second method:
http://search.digikey.com/scripts/Dk...me=255-1117-ND


Note: One possible problem is with an integrated turbo timer. All that would be needed is a relay that is activated by the status output wire, grounding the main relay. This will ensure your main relay always functions during turbo timer and remote start modes, and that the latching kill relay works too. The other is that the alarm's pulse isn't long enough to activate a larger, slower latching relay. One fix is to lengthen the pulse via this small circuit. I used this circuit (with different cap/resistor values) to keep my electronic exhaust cutout open between shifts, since it closes below 60% throttle...and closes extremely fast. The last problem - your alarm may "forget" to disarm the relay. Worst-case scenario is you have to hit unlock again.

Tekkaboy

iTrader: (2)

Very good info, I never knew they made latching relays.