viper 791xv door locks problem
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=66086
Printed Date: July 22, 2025 at 9:01 AM
Topic: viper 791xv door locks problem
Posted By: dmcdlrn
Subject: viper 791xv door locks problem
Date Posted: November 11, 2005 at 10:17 PM
Ok, so this is the second 791 I have installed. I put one in my summer car, but this year I picked up a beater and put one in it as well cause I like the alarm. This time when I did it I am having trouble with door locks. I have a door lock system that has a white wire for unlock and a brown for lock.. both negative triggers. Seems obvious that one would just hook them up to the appropriate alarm wires (which I did) and even diode isolated them from the positive pulse. But.. for whatever strange reason they will lock, but not unlock, and sometimes it won't lock after trying to unlock. So after messing around with it I found something that seems rather strange... the module is putting out a constant ground on blue I think (whichever is - unlock) This seems like maybe the module is screwed up. I'm about ready to go nuts.. everything else works great including remote start and arm and disarm, but I can't get that to work for the life of me. I'm inches away from taking the cover off my other car and pulling the module out. Any help is greatly appreciated!!!
Replies:
Posted By: mo12v
Date Posted: November 11, 2005 at 10:32 PM
You forgot the Obvious also: YEAR, MAKE & Model of Vehicle ------------- MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: dmcdlrn
Date Posted: November 11, 2005 at 10:35 PM
oh well thats cause it doesn't matter... the power locks are after market. But it is a 1993 subaru loyale 4WD Locks work great if you touch the white or brown to the ground or to each other... but if you connect them to that remote its a different story... I'm really concerned with the constant ground on the negative unlock wire! Is this normal or is my module messed up... it doesn't seem to follow suit with the manual.
Posted By: mo12v
Date Posted: November 11, 2005 at 10:41 PM
Some Aftermarket Doorlock Actuator Kits require a Stronger GROUND than the 791 puts out..............You may need 2 SPDT Relays to supply the GROUND Pulse
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MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: dmcdlrn
Date Posted: November 11, 2005 at 10:43 PM
ok, thats something I can try... not sure that this is the case with mine... If I don't hook the unlock up to that crazy constant ground wire then it will always unlock... seems to me it has plenty of ground there to do that... plus, the negative unlock that I speak of has a perfect 0 ohm resistance to ground... straight at the pin... meaning if I pull the harness and just test it at the module its grounded on that pin.
Posted By: mo12v
Date Posted: November 11, 2005 at 10:58 PM
You may have verified the need for Relays by your Test of the LOCK / UNLOCK wires pulsed to Chassis Ground..............
Some units will give a Stronger Ground / Positive on LOCK or UNLOCK than the other LOCK / UNLOCK wire
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MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: dmcdlrn
Date Posted: November 11, 2005 at 11:03 PM
Ya, I can try that, but I'm still stuck on the concept of the unlock wire showing constant 0 ohm ground. According to the manual that should offer a - pulse for unlock and a + pulse during lock. But it doesn't. I't just provides a constant ground. If I touch either the lock or unlock wire to that wire on the harness it imediately locks/unlocks the doors and freezes my unlock system until I take it off that wire.
Posted By: mo12v
Date Posted: November 11, 2005 at 11:06 PM
And is that with the Lock wire Hook up ??
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MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: dmcdlrn
Date Posted: November 11, 2005 at 11:07 PM
nope. I can pull the little harness right out of the module and test it at the pins... and it shows ground at the pin.
Posted By: mo12v
Date Posted: November 11, 2005 at 11:18 PM
791 will not know if you require POSITIVE or NEGATIVE Pulse until both wires are hook up:
Read: https://www.directechs.com/techtips/pdfs/resources/security/directed_techtips/1041.pdf ------------- MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: dmcdlrn
Date Posted: November 11, 2005 at 11:32 PM
I have hooked both wires up and it didn't work... only lock... I know you are saying that I may need relays, and I read that guide and I see what it says too, but I still maintain that as soon as I hook a relay network up its just going to snap that unlock relay closed and leave it cause its constantly grounded. I want to know if this unlock wire is supposed to show that constant ground or not. As another test I ran the factory alarm arm and disarm outputs to the lock and unlock wires of my door locks and it worked fine.
Posted By: dmcdlrn
Date Posted: November 12, 2005 at 1:38 PM
Yup, swapped out the module from my other car and it works fine... appears I got a broken module. Glad I spent 5 hours of my time drawing diagrams and revisiting my dc electronics basics in hope I was just having a brain cramp. Oh well, thanks for your help!
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