Factory Alarm - 99 Silverado

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=18284
Printed Date: July 18, 2025 at 7:33 PM

Topic: Factory Alarm - 99 Silverado

Posted By: captntech
Subject: Factory Alarm - 99 Silverado
Date Posted: August 30, 2003 at 7:54 PM

Just installed a Crimestopper RS900 in a '99 Silverado, no problems. However, the remote lock/unlock doesn't arm/disarm the factory alarm. The factory remote allows you to remotely lock the doors and it arms the alarm. The RS900 will lock the doors but not arm the system. I tried to take the neg output from the lock (before it got to the polarity inverter - Silverado locks are positive and RS900 puts out ground pulse) and send it to the doorpin as the wiring diagram I downloaded stated that a ground pulse from the doorpin at the same time you lock the doors would arm the system but it didn;t work - in fact it messed up the locks and they would immediately unlock after a lock command. Has anyone figured out how to incorporate factory arm/disarm with door lock/unlock on these GM vehicles? Thanks for your boundless wisdom!

Installing same in a Trailblazer tomorrow, but it uses the GMDL1 module which handles locking and arming automagically so it won't be an issue (I hope)!

Replies:

Posted By: JWorm
Date Posted: August 31, 2003 at 1:24 PM

I think you would need to use two relays to arm the alarm with the door closed in order to have a strong enough pulse on the door trigger and to keep things isolated and from feeding back to each other. Or you could just lock the truck with the door open as you are exiting it. Thats what I usually tell customers.

Never tried it, but I suspect the following would work.
Relay 1
86 - +12v
85 - green lock wire from alarm
87 - +12v
30 - to lock wire of truck

Relay two
86 - +12v
85 - green lock wire from alarm
87 - ground
30 - to drivers door trigger (tan/stripe?)

Disarm is easy, light green at the BCM. Hook up the disarm wire from the RS900 to it.

Posted By: captntech
Date Posted: August 31, 2003 at 3:13 PM

OK, persiverence (sp?) always pays off! Spent an extra hour and went back into the whole thing and discovered I had the wrong doorpin wire. Further testing and removing the driver's kickpanel revealed the REAL tan doorpin wire. Tapping into it with the Crimestopper RS900 rearm wire works great. Even rearms the factory security during a remote doorlock. Excellent! Now to figure out how to start the rear defogger using the trunk button! posted_image