GMC sierra and viper 850 lock 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=76322
Printed Date: July 05, 2025 at 11:25 PM

Topic: GMC sierra and viper 850 lock problem

Posted By: tk064
Subject: GMC sierra and viper 850 lock problem
Date Posted: April 16, 2006 at 4:01 PM

I just installed the viper 850 in my extended cab 06 GMC truck. I did a minimalist install, (no remote start or wires hooked up to the parking light circuit). Channel 2 output to a custom toolbox. The alarm and toolbox locks are working fine, but the door locks work sometime. I went back and installed a relay in between the viper and the GM-Dtbus to make sure I was not getting a resistered ground to the Dtbus. This did not make any difference. I am grounded to a bolt under the dash. Any help would be appreciated.

As a side note, I still get a taillight flash with the lock/unlock button, I assume this is being triggered by the data wire. If I switch and grab the lock wires out of the door, (I don't want any light flash), would I grab each door independantly and how many relays would I use to prevent any backfeed from the factory circuit.

Thanks for everyone .

Replies:

Posted By: sparkie
Date Posted: April 16, 2006 at 8:55 PM

Take your grounds off any part of the dash and attach them directly to the kick panel. Scrape the paint away and make a secure connection. Use a good source of power from the ignition harness for main power for both the alarm and data module. Red or RED / white in the ingition harness. Make sure that your module is programmed for the correct body type to correctly activate the door locks. The dash is a very, very poor source of ground in these trucks despite what some people think. Just because it's metal doesn't mean its a good ground. I s fix many installs for this same problem. Solder any connections for your data module.

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sparky

Posted By: tk064
Date Posted: April 17, 2006 at 6:24 PM

I grounded to the bolt where the cast aluminum sub fram was bolted to the A-pillar. I then tried running a wire to the grounding bolt where the motor grounding strap is attached. I am still having the same problem. I did two trucks, one is working fine. Or course I received 2 different GM-dtbus modules. The one I am having problems with is the one pictured here https://www.caralarmz.com/. The GMDL-BP is working normally. I am going to try to reprogram the module. Thanks for your response.

Posted By: sparkie
Date Posted: April 17, 2006 at 7:31 PM

You may have a bad module. I would suggest pulling it out and replacing it with a GMDL BP. They work great. The ground is still an issue. Don't trust GM grounds. Always use your own and it MUST be into the chassis after the paint is scraped away. The white metal in GM dashes isn't good for grounds.

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sparky