Factory disarm output pulse needs relay?

Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=43341
Printed Date: May 14, 2024 at 3:29 PM

Topic: Factory disarm output pulse needs relay?

Posted By: ExitVector
Subject: Factory disarm output pulse needs relay?
Date Posted: November 19, 2004 at 1:42 PM

Hi all,

Please go easy on me if this has been covered in other posts, I looked for about an hour and a half and my question is still unanswered. Also, if this should be common knowledge, then again, go easy...

On remote starters with a factory disarm/rearm (-) output pulse, why do they tell you to use a relay? The pulse from the module will trigger the relay's coil, closing the pole and contacting the factory disarm/rearm wire to ground. Why is a relay needed, the negative pulse from the module not adequate to actually trigger the disarm?

The reason I ask is, my car's OEM factory alarm has recently been going off at random times. The ignition switch on my car had to be recalled, and when the dealer replaced it, they cut out the remote starter wires. This I understood because they cannot support aftermarket parts. I reinstalled the remote starter myself, using the old ignition switch harness that they let me keep. The remote starter works like a charm, but the other night I armed the car and went to bed and I woke a few hours later to my horn going off. The car is a 1999 Honda Accord EX, and the only thing I can find is that the disarm wire is not wired with a relay. Although I am highly doubtful that this would cause the alarm to sound when the remote starter should be at rest.

HELP!

Replies:

Posted By: Velocity Motors
Date Posted: November 19, 2004 at 5:38 PM

The only time that the OEM system will go off is if it's triggered by a door opening or the trunk/hood. If your getting a false alarm from the OEM alarm, then it would not be the remote starter's fault as the OEM disarm wire is only active when you initiate the remote starter sequence. If you want to retain the OEM security system you'll need to see where the false alarm trigger is coming from or if you don't want to retain the OEM security, just jumper the OEM disarm wire to ground and it will never arm on you.

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

Posted By: ExitVector
Date Posted: November 19, 2004 at 6:14 PM

OK cool. Thank you! I'd like to keep the factory system, can't have too much protection I always say. What about the relay for the factory disarm pulse? What's up with that?

Thanks again!

Posted By: NowYaKnow
Date Posted: November 19, 2004 at 9:59 PM

"What about the relay for the factory disarm pulse? What's up with that?"

Most OEM disarm outputs are low current outputs from the module. Normally it doesn't take much current to disarm the OEM alarm, so you can get by with just hooking them straight to one another with no relay. On rare occasions the output isn't enough to disarm the factory alarm, and you would need a relay to make the ground signal stronger. Sometimes the disarm wire is positive or needs a resistor in which case a relay would be needed. With that said, like Jeff said this probably isn't your problem so I wouldn't worry about it.

Mike