[McOlaf]

She had the problem since I have bought it, but would like to have it sorted...

Both rear doors are not locking, not with the remote, not with the key...

I have to push the buttons down manually....

Once the doors are locked, they will not unlock with either the key or remote..

What can this be?

[Leeky]

Its most likely the central door locking motors in the respective doors.

Easiest thing to do first would be to remove the door cards on the rear doors, and then with a voltmeter check you have power to the door locking motors. If there is power, but they are not operating they're likely stuffed.

That said, its entirely possible the linkages have come loose, or the motor is loose and as such the full movement isn't able to happen and the doors aren't locking.

If the motors are working, you will see this very clearly with the door card and door membrane removed. If they don't move at all, but have power they are knackered and need replacing...

You'll find plenty in the scrapyards these days.

[matt-m]

my drivers rear does the same thing bud check the wiring from the b pillar to the door as well

[McOlaf]

I will have a look in that next week...

Not that it is a problem right now.. I can close them from the inside, but hey, it's built with it, so it has to work.. can't stand it that things don't work...

It's just so funny, at home I don't lock the rear doors, just press the remote, and walk off..
In the morning when my daughter has to go to school she makes a game of it to just open the rear door.. and yes, the alarm starts to scream them.. a siren, AND the horn... GOOD MORNING!!

[Leeky]

Its ALWAYS annoyed me the way GM alarms work... The key, and the fob SHOULD both disarm the alarm.

I had a facelift 2.6 estate Vec B SRi, and the remote fob battery ran out, so used the key to lock the car, only every time you unlocked it with the key and opened the door the alarm sounded until you put the key in the ignition and turned it on!! NOT GOOD!