Door lock issues

I own a 2000 Chevy Monte Carlo and I’m having a problem with the door locks. If I press the lock button on the remote one of three things will happen.



1. the horn sounds and the doors lock.

2. the horns sounds and the door locks do not engage - if the door or trunk is opened, the horn alarm (panic button) sounds

3. nothing



The problem is intermittent and in when the locks are not working, the inside buttons do not work either. My mechanic cannot find a problem other than replacing the battery because of a dead cell.



Did the mech actually tell you the (vehicle’s) battery has a dead cell and needs replacing?

It is possible the power door locking MODE needs to be either changed or re-programmed.

Perhaps even the security system is interfering.

Has the remote been dropped on a hard surface at any time?

When was the remote battery last changed? (if the remote’s battery is to be replaced, it will need to be re-programmed)

All GM Dealers have as a “essential tool” a remote tester,it can be used to verify a signal comes from your remote as each button is pushed (condition 1. sounds like normal operation)

I’ll try the mode programming. I don’t think it’s the remote. The buttons inside the car don’t lock/unlock when the system is acting up.