Printer Friendly Forum Posts - Pin switch and mercury switch

Im trying to hook up a mercury switch on the hood and a pin switch on the trunk. The alarm is a viper 690. I hooked up the mercury switch and had it working then i did the pin switch and now neither work. I cut the wire on the pin switch and the mercury switch still doesn't work. This is pissing me off. Its probably really simple. Do I need a diode to isolate them? If so how do I hook up the diode and which one? For the mercury switch does it matter how you hook it up as long as when you open the hood there is continuity between the two wires?

Thanks for all the help!!!! This should be my last question.

Clay G.

the mercury switch one side to ground the other side to - alarm input the trunk I would also use a mercury switch most pin switches do not last and you dont need diode to isolate them. posted_image

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tom cat

I'm curious to see how the mercury switch works, I've always heard about them, but never worked with one. I installed 2 hood pin switches for the hood in 2 cars, and they both failed within 6 months. In my opinion, they suck for the hood. Maybe they're a little better for the trunk.

I've always diode-isolated the hoodpin and trunk wire in the past, though, because I usually wind up hooking them up to the same input on the alarm. I use diodes because otherwise when I open the hood, the trunk light and indicator would go on.

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Q: What's the best nation in the world?
A: Donation! Donate to the12volt.com

Before you install the pin switches, use a lithium grease or bearing grease on the threads and the male spade connector to help against corrosion. 9 out of 10 times the hood pin fails because the connector and the pin itself gets corrosion and it breaks off.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Or customer that fix on thier car all the time they slam the hood or trunks down. Most installers I work with don't use them because the shock sensor usually picks up that much impact. But if the customers wants it I guess it is a good thing. If you are using a DEI alarm I would use the instant trigger wire to hook up both trunk, and hood. Like someone said previously just diode isolate it so the alarm brain doesn't get "confused."

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~The Rookie~
Rookie of the year that is...
Don't let the smoke out of your equiptment..it doesn't go back in.

if you can get the mercury switches that are clear, not the black ones, they are great, but you must use dielectric grease on all outside connections or you will get corrosion and you'll be chasing problems. never use pin switches, they suck!

also location of mercury switch is important when parke don hill car wont start because viper thinks teh hood is open!

Clay G,

rckid] wrote:

o I need a diode to isolate them?

Yes . . .

rckid] wrote:

If so how do I hook up the diode

Striped side (anode) of the diode faces the switch.

rckid] wrote:

and which one?

Any 1N4001 - to - 1N4007 one amp diode will do. For your general information, the 1N4001 has a 50 volt rating, and the extreme end of that family is rated at 1000 volts.

rckid] wrote:

or the mercury switch does it matter how you hook it up as long as when you open the hood there is continuity between the two wires?

The mounting location is more important. I hope you have affixed the device so as the attack angle is immediate upon the hoods elevation.

Regards

EVIL Teken . . .

I just put in 2 1N4001 diodes the way you said to and it still doesnt work. When i arm it the remote says everything is ok. While its armed and I open the hood or trunk nothing happends. Then everything is closed and I disarm the alarm the remote says the hood or trunk is open and the sensor is going off. Whats the problem. I have the switches hooked up right. On the pin switch I have the ground part hooked up to ground with a wire and the trigger wire hooked up to the end of the switch with a male connector. The diode is connected with the stripe tward the switch. The mercury switch is connected with the black wire to ground and the red to the same trigger wire from the alarm that the trunk is hooded to. I put a diode in the red wire with the stripe toward the switch. I have the mercury switch set up so when the hood opens, the red wire had continuity to ground. Anything sound wrong? I think its right.

Thanks,
Clay

rckid] wrote:

n the pin switch I have the ground part hooked up to ground with a wire and the trigger wire hooked up to the end of the switch with a male connector.

That is incorrect. The pin switch should only show ground when the hood is ajar / open. As I understand what you have stated, you have grounded the switch directly to the chassis.

It should only show ground with the pin in the up position, and not in the down position. Which you show ground in the up and down position.

Regards

EVIL Teken . . .

I have the pin switch mounted to plastic so i had to put a wire on it so it could ground when the trunk was open. So im pretty sure I have that right. Anything else look wrong? I can't figure it out. This is the last thing I have to do and its pissing me off!!

Clay

Anyone have any ideas?

Which wire are you using from the alarm? The blue wire? Did you see that in the install guide, it says that you have to reprogram the remote if you use the blue wire for the hood or the hood and trunk? Maybe that's a problem?

If not, I think you need to do some process of elimination. Hooking up two sensors to one wire usually isn't this complicated, so I think you need to start "basic", and then add stuff on until it messes up. For example: Just hook up the mercury switch (without a diode) to the input wire of the alarm, and see how that goes. If it works fine, then add the diode in. If that works fine, then add the trunk pin, and then the diode. If it messes up somewhere in there, then maybe you'll be able to find the problem. I'm wondering if something is messed up because you used plastic to mount the pin switch (although I see that you used a wire to ground it).

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A: Donation! Donate to the12volt.com

rckid] wrote:

I have the pin switch mounted to plastic so i had to put a wire on it so it could ground when the trunk was open.

Clay,

How and where is this wire affixed to the pin switch?

Regards

EVIL Teken . . .

The wire is on the threads of the pin switch. Where it would normally be grounded to the body if it was mounted to metal. That is not my problem. I disconnected both switches. Then i armed and disarmed the alarm. Everything was closed and it said the trunk and door was open. I knew this wasn't right so i disconnected the battey and that fixed it that. So i connected the mercury switch on the hood and that worked fine except after I had triggered the alarm a few times it didn't work anymore. After I started the car and let it run for a little bit, i tried it again and it worked fine. Im thinking this might have something to do with the battery. Do I need to run a constant power directly from the battery because how I have it I just tapped into the fuse box. I know this is not the best way but it was easy. Im thinking that when the voltage goes down a little the alarm doesn't know what to do. Is this normal?

Thanks,
Clay G.

Clay,

How you have explained the situation sounds to me like the Viper alarm system has simply bypassed the zone / area, because it thinks that area is defective.

Viper calls the feature NPC (Nuisance Prevention Circuitry) the federal law calls it Noise Abatement. To test that theory, simply count the number of times the unit ignores that zone.

If the number of zone(s) tripped are consistant in the time you notice the sensor as being inactive.

That will confirm my belief.

Regards

EVIL Teken . . .

Do you have a DMM (digital multi-meter)? If so, set it on continuity test. It should emit a piezo buzzer sound when the two leads are touched together. Clip one lead to the wire at the wiring harness to the alarm. Clip the other end to any grounded metal spot under the dash near the alarm. It should not be beeping at this point. Now open the hood. If your switch is connected and functioning properly you will hear the continuity buzzer when you lift the hood. Close the hood and the sound should stop. Now open the trunk. If the trunk pin is properly connected and making a connection to ground when you open it you should hear the buzzer again. If this all works correctly you may have a bad input on the alarm brain. Or as Teken says it could be bypassing the zone. Good Luck.

Im pretty sure it was bypassing the zone. I forgot all about that. Thanks for everyones help. I have it almost working. I didn't feel like messing with it today. I just have the hood hooked up now but the trunk will also set it off because it is the same trigger wire for the doors.

rckid] wrote:

Im pretty sure it was bypassing the zone. I forgot all about that. Thanks for everyones help.

Good to know things worked out. But, I would definately verify all aspects of the installation. As it has been pointed out in how to do so for specific area's.

Regards

EVIL Teken . . .