multiple car alarm sensor

Hi all, I'm new here and I just installed viper 350 plus to my 2000 celica today by myself. I have a question about connecting multiple external sensors (shock, tilt, glass, etc.) to it. Since there is only one 4-pin socket sensor harness on the brain, can I just connect multiple sensors together? Do I need a diode? I saw some posts about using diodes to isolate sensors from trunk pin, but not sure if necessary to isolate sensors from each other. Further, if diodes are must, it has input wires to the brain which marks (-). What direction of the diode should I apply? And, how can I test I put them into the right way not the wrong direction? Thank you for reading my dummy questions, I'm really new in these. Thanks a lot!!!!

As this diagram, diode bands towards sensors. multiple_sensors.bmp Please note the diodes are 1N4004 Radio Shack etc., and the black wire might be orange. As a precautionary note juggling more than one sensor against another (getting the sensitivity right) is a pain, lots of false alarms. I stick with what's onboard, e.g. shock and add a 508d, proximity/field effect sensor. You really don't need any more.

By the way, the answer to your second question is yes in both cases. Here is an example of sensor plus window closer wired to trunk trigger, also note the diodes in the other direction blocking the orange wires, this is because of the 530t window closer relay effect. Also if that blue wire is also for hood, then diode apart those as well, otherwise a faulty hood switch can pull on the trunk light and do in your battery. 43B_diodes.bmp

THanks alot! really helpful~ BTW, 1n4004 diode is 400v. I have some 1n4001, which is 50v. can they work? is the signal in the wires that high? thx again!

Yes on the sensors but I wouldn't use them as anti surge with relays. Use up your 4001 and buy 4004 in future. In fact most non-specialists only stock 4004 nowadays. Has the US version got a white plug in the centre console next to the fusebox? You have to drop the head unit but that's the factory alarm point, lock/unlock door hatch and hood triggers, lights etc.

Hi Howard, How many sensors can we splice in for each 4 pin port? I have read some where some one said two. More than that I would need a relay. How would I wire the relay if one is needed? Thanks.

Your wasting your time, all you need is a 508d properly set up, all the others will interfere and cause false alarms, up to 2 at one port plus diodes to separate the trigger wires.

Once again you are correct Howard. My alarm came with the dual shock and glass sensor in one. I am having getting it right. If I get the shock sensor right, then turn the glass sensor up, it would trigger with much more sensitivity. I also have the motion sensor, which I set it so that you have to come real close to the front windows to warn, and practically stick your arm inside the car to full trigger. But Howard, the rear area of my car is not cover by the motion sensor. I have it mounted sitting on carpet between the auto shift console and the hand brake console with the arm rest above the hand brake console. I would think the best place is the dome light area but I don't want to take the head liner off and extend the sensor wires. Would you recommend moving the motion sensor behind the hand brake console? Where do you usually mount your motion sensors in your professional installs? Thanks.

When I can I always mount in the roof, extend the cables if required. You will never get the volume exactly right. In all my years the only vehicle I ever got right out of the box was an X5, mounted as you thought just behind the dome light and it worked perfectly as you walked around the car yet it had heavy tint on the back and side windows. BTW your first line, I'm always right this is 35 years experience telling you, learned the hard way.