2000 Blazer Alarm Going Off

2000 Blazer LT 4wd, 118000 miles

During a severe thunder storm the factory alarm went off. I was unable to shut off the alarm with the key fob. The power door locks did not work either with the door switch or the key fob. I disconnected the battery and let it sit for 30 minutes.

After I reconnected the battery the door locks worked using the key fob or door switch. I took it for a drive with no further problems. About 10 minutes later the alarm went off again. I could hear the door lock solenoids attempting to lock/unlock the doors and there was a clicking (relay?) under the dash. I disconnected the battery again, after the battery was reconnected the power door locks were still not working. The truck starts up and runs normal, everything seems to work except for the door lock?

I checked the PW fuse, it was fine. The battery is fully charged at 12.6V. I’ve disconnected the battery and will have another look at it tomorrow. There was nothing useful in the Owner’s Manual and the resync procedure did not work.

Any thoughts or suggestions would be appreciated.

Ed B.

Update: Before driving to work this morning, I cleaned the positive and negative terminals. The locks worked and the truck ran normally during the 30 min drive to work. After reading the Owner’s manual closely, I discovered the Theft Deterrent System can be disarmed by locking the car with the doors closed. The system is armed by locking the doors with a door open, i.e. pressing the lock switch when exiting the vehicle.

Final Update

7/9/11 - No further problems with the alarm or the door locks whether the Theft Deterrent System is armed or disarmed. Hopefully leaving the battery disconnected overnight was the fix.

This morning I closed the door before locking the truck with the key fob. So far (~2 hours) the alarm has not gone off.


After a light rain the alarm went off again. The door locks do not respond to the door switch or the key fob. They are not cycling this time though. I’ve disconnected the battery for now.

If anybody has experienced this with a GM vehicle and has a fix or work around I would love to know.


Well it happened again today (10/19/11). The alarm went off around 5:30 pm after an entire day of rain and drizzle. I’ve disconnected the battery overnight.

Possibly related, on Saturday the “Service 4wd” light came on. I restarted the truck and the light stayed off. After driving 3 or 4 miles the “Check Engine” light came on, I’ve had the truck 8.5 years and this is the first time it has occurred. I disconnected the battery and the CEL has not reappeared.

At this point, I’m not too worried about the truck getting stolen, so does anybody know how to disable the alarm on a 2000 Blazer.

Ed B.