791xv trouble

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=125393
Printed Date: July 13, 2025 at 3:53 PM

Topic: 791xv trouble

Posted By: crazziazz
Subject: 791xv trouble
Date Posted: January 01, 2011 at 7:40 PM

Hello guys,

I have a 2000 expedition. I got a 791xv viper alarm for next to nothing.
I know this is a fairly good piece. Everything is working great expesct for start.

Yesterday did great started up ran fine. Today It starts up but then shuts down. All this with key in cylinder. Tach is on pink/white straight on coil.

Reprogrammed tach but noticed when I did I had to rev eng A little for it to pick up.

Any suggestions would be greatly appreciated

Replies:

Posted By: t&t tech
Date Posted: January 02, 2011 at 6:11 AM

You may have to adjust the tach threshold to a lower setting.

Posted By: crazziazz
Date Posted: January 02, 2011 at 9:00 AM

Is that in the programming remote start options? I already tried turning the threshold off or on.

Posted By: t&t tech
Date Posted: January 02, 2011 at 10:28 AM

No it's on the outside of the brain in the form of a jumper check the base of the brain to verify which is the parking light and which is the tach.

Posted By: crazziazz
Date Posted: January 02, 2011 at 10:33 AM

yes i tried that. Just so strange. I should have know better. A used alarm. Bad thing is i don't have a bit writer. Don't know if anything is locked.

Posted By: crazziazz
Date Posted: January 02, 2011 at 4:50 PM

I changed the remote start setting to voltage instead of tach. Working good now. Been awhile sine I installed. I quit installing in 05. A little behind. Never really did many vipers all prestige(Aps996 etc). But this site has always been the best.

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