Viper 791xv Problems

I am going through inspection in Quebec for my car and installed DRL which was not too difficult, tapped power wire from fuse box under DS dash. Then I went to finish job and reconnect battery my alarm siren keeps going off. The funny thing is there are no lights and no LED blinking (like alarm usually does) and the remote pager will not shut alarm off (Viper 791xv) or communicate with car anymore. This is despite everything I have managed to think of...
-tried valet switch dis-arm
-change pager battery
-disconnecting battery and reconnect
-disconnecting harnesses from alarm brain
-charge battery fully
-re-grounding the siren

This is driving me crazy, I have many other repairs to do on my car to get it to pass inspection and I do not need this :shock:

Any ideas??

What year, make, model car?
Does the 791 LED ever come on? While siren chirping, when armed, valet, anytime?
What common connections for the 791 got disturbed during the DRL install? Power, ground, light flash, etc.
With the FOB in 2-way mode, does it react to anything the system does?
Check the fuse for the 791.
If you connect the 791, and the siren sounds, let it run until it stops. Either 30 or 60 seconds depending on programming. Does it stop on its own, and what does it do? Is the LED flashing the ZONE of the trigger?

There's some ideas. I'd start by letting it time-out on its own, and then see how it behaves. I have a 791xv in one of my trucks. I'm very familiar with the 791. I should be able to help, but I've never had mine do what yours is doing.

I have a 1993 Mazda MX-3 it has been installed on the car for almost 10 years without any big problem like this. The LED does nothing, doesn't flash or light up. The alarm sounds when I connect the negative battery cable, it will not shut off using the pager or the valet button dis-arm method. When installing the DRL I didn't interfere with any alarm connections only my 12v from battery and am using 12v power from fuse box for DRL power. I have not tried letting alarm time out, I'la give it a shot later today. Fuses seemed ok when I checked them. I disconnected all the connections at the brain and reconnected without any difference. Thanks for help I hope I can figure this out!

see if it will time-out and stop on it's own. You can disconnect the siren if you don't want the racket. After a couple of minutes, reconnect the siren and see if it stopped.

The 791 "remembers" the last state it was in when power was cut, and that state is resumed upon power-up.

Not sure why it isn't flashing the zone on the LED. It should be. Is it flashing the park lights with the siren? It should be.

See if it stops on its own, and go from there.

The parking lights and LED don't flash which is unusual, will try layer today and see what happens, thanks!

I let the alarm run out, seemed to work after leaving it for a while (siren ground unhooked). Then went to open the door the alarm began to sound at low volume, then went to start and it re-alarmed. The LED is blinking now, will try to upload video.

I can't view the video. Probably this POS tablet.

If it "re-alarmed" when you started it, it was probably still armed, and triggered from the ignition. IGN trigger is Zone 5, 5-blinks on the LED. Opening the door is Zone 3, 3-blinks.

Now that it seems to be normal again, but is ARMED, try disarming it with the valet button. You have to get it in the disarmed state before you can re-learn the FOB.

Will it now arm and disarm from the FOB? If not, I would try re-pairing the FOB to the 791. The procedure is in the Install guide. HERE.

It sounds like you're making progress. At least the LED is active again, and the system responds to triggers. Now you have to get it to disarm.

When I let the alarm run out, I open the door it restarts low volume, I was able to communicate via pager and doors locked it says the alarm was armed and the LED started blinking and it let me disarm but the alarm keeps going! The pager only worked for like 15 seconds now it says out of range again. I'm so frustrated! What could be wrong?!

Bet there's a constant 12V+ getting to the siren somehow.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

howie ll wrote:

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Bet there's a constant 12V+ getting to the siren somehow.

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My first thought as well. Disconnect the positive DRL wire and see what happens.

Correct DLR wiring, + to ignition, - to headlight(side running lights UK) provided they go to 12V+ when on, shouldn't affect anything else.


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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.