problem with upgrading factory alarm

Hi guys, I'm hoping you guys can help me out with a problem I'm having. I have a 1987 Toyota Supra with a factory alarm that triggers when the doors, hood, or hatch are opened. I wanted to upgrade this without getting an aftermarket alarm so I bought a DEI glass break sensor and a 504M DEI shock sensor and tied them into the factory triggers. The glass break sensor is working perfectly. I am having problems with the 504M shock sensor though. The alarm will not arm with the shock sensor plugged in unless I take the yellow wire (supposed to ground when the ignition is at off and provide 12v when the ignition is on) to a direct ground. When I take this wire to a ground the alarm and sensor work perfectly, but the alarm is able to arm while the car is running. The yellow wire is tied into my cigarette lighter, which I believe may be providing trace voltage because it is also tied in with the clock in my car, therefore not providing a good ground. So, I tried grounding the green wire for the warn away function which isn't used with my factory alarm and the alarm worked perfectly. My only concern is if it is OK to run the green wire straight to ground since I measured 12v on it with the car running. Are there any potential risks to running the green wire with 12v to ground? Thanks in advance for any help.

The yellow ignition wire needs to see ignition so it knows that the car is on and not to arm. It sounds like you have a bad ground for the shock sensor? Where did you connect the power / ground for the sensor?Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

Thanks for the reply, I connected the red power wire from the shock sensor to the 12v constant from the radio. I connected the yellow ignition wire to the cigarette lighter wire. I think you are right, the problem is that I have a bad ground for the shock sensor. With the ignition off the yellow wire still reads .7v, and the cigarette lighter still puts out .7 volts. The strange thing is that when I ground the green warn away wire and do nothing else the alarm works perfectly, shock sensor works perfectly, and it won't arm with the ignition on. Why would grounding the green wire change anything?

I would assume it's backfeeding through the green wire to get the ground. Where did you ground the shock sensor? Also check your battery ground for corrosion / loose terminal.Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

The shock sensor did not have a dedicated chassis ground wire like the glass break sensor did. It had the red power wire, the yellow ignition wire that is supposed to ground when the ignition is off, and the two trigger wires.

You might need a "true" ignition wire. Thats a wire that goes to ground when there is no power on it. Some ignition wires just goto zero volts or nothing(no ground or no +12volts) The best place to get a "true" ignition wire is the ignition harness of the car. You can use either BLACK / YELLOW or BLACK/ orange coming off the ignition switch.

Sorry, I thought the yellow wire you were referring to was for the factory alarm. What flobee said... lol. Make sure to add a fuse if you tie into those wires since they are most likely rated for a higher amp draw than that little sensor wire could ever handle.Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205

Thanks for the help. I don't really want to cut into the ignition wires so I ordered a SPDT relay. I'll just use that to switch the yellow wire from the shock sensor from 12v to ground when the ignition is turned off. I already have all the wires I need in the harness for the shock sensor so it should be pretty easy to install. I hope this fixes the problem.

Make sure to wire it so that the relay is activated by the ignition to send 12v to the yellow wire and then ground when the ignition is off. That way the relay is activated the entire time the ignition is off causing it to drain the battery. Someone can correct me if I'm wrong (not 100% awake yet) but it should be as follows: Pin 30 to yellow wire Pin 87a to chassis ground Pin 87 to 12volt ignition source Pin 86 to 12volt ignition source Pin 85 to chassis ground Kenny

Owner / Technician

KKD Garage LLC

Albany, NY 12205