Driving door lock relay with two inputs

My RKE supports two-step unlock but does not support ignition unlock on the second-step. In other words, when I turn the ignition on, all doors lock. When I turn the ignition off, only the driver's door unlocks. The passenger unlock output drives a relay that grounds the single-wire system in the car. What I'd like to do is augment this with a negative pulse on ignition off. I was looking at this relay diagram and thinking that I could tap the passenger unlock into #85. I can quite place why but I wonder if this is not going to work. If the ignition is ON, and the passenger unlock goes to ground, then is that a short even though we are going through the RC circuit? Otherwise, I could use two relays, and tie #30 of the AUL relay into the ground side of the coil on the existing door unlock relay. Do I need to diode protect the two grounds coming together? Does anyone have any other ideas or a cookbook diagram for solving this scenario?

what kind of vehicle is it? a lot of the newer GM vehicles do this and it's a user programmable feature, you can have it unlock drivers only, all doors or none....i usually program these vehicles to none because when your RS times out it will unlock the doors.Kevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

The vehicle is a 1999 Mazda Protege. The RKE is a Black Widow 852. This is not listed as a programmable option. What is this RS you mention timing out?

RS=Remote starter   on the GM vehicles programmed with Ign controlled door locks when the starter shuts down or is turned off it will pop the doors open, which is not desirable...   did you check with a dealer to see if thats normal for this model of car, that it opens only the drivers door?  that may be the way it was engineeredKevin Gerry

Certified Electronics Technician

MECP First Class Installer

Owner/Installer

Classic Car Audio

since 1979

Just to clarify: 1) The vehicle is not GM. 2) The vehicle does not have factory keyless entry. 3) The vehicle does not have remote start. The only device in the system that would be programmable is the Black Widow 852 RKE, which does not support ignition unlock on the passenger unlock wire. This behaviour is not programmable on this unit. That is why I am pondering the addition of a relay to solve this issue. So... I am still wondering if I need to isolate the two ground inputs to the relay.

Works nicely.