2005 Chevrolet Silverado Automatic door locks

Dannie, power lock actuator faulty. Check the attached links,instruction and guides, Good luck
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Probably is the actuator. Common problem. The actuator is part of the complete door latch. Hopefully that is what you got from 'Dorman'.

The power windows an power locks are controlled by a module , DDM - driver door module . As far as the locks locking when you put the vehicle into reverse an unlocking when you put the vehicle into park , that's how there are suppose to work , automatic lock an unlock feature . When you put the vehicle into any gear from park the locks should lock . Did she hit window lockout function ?

The power door lock system consists of the following components:
• The driver door module (DDM)
• The passenger door module (PDM)
• The body control module (BCM)
• The driver information center (DIC)
• The rear door lock switch
• The door lock relay
• The door unlock relay
• The liftgate lock relay--utility vehicles with liftgate only
• The reversible door lock actuators in each of the doors and liftgate
• LOCKS 20A fuse (rear lock/unlock relay supply voltage)
• ECC 10A fuse (liftgate lock relay supply voltage .

Programmable Automatic Door Locks
The automatic door lock feature can be programmed to control the door lock system. The automatic door lock feature is factory programmed to have all doors lock and unlock. For detailed instructions on programming the automatic door locks, refer to Vehicle Personalization in Personalization.
When the automatic door lock feature is programmed to control the door lock system, the driver door module (DDM), passenger door module (PDM) and body control module (BCM) will lock the vehicle doors if the following inputs are true:
• Ignition 1 input is active.
• All door jamb switch inputs are inactive.
• Cargo door or liftgate/liftglass ajar inputs are inactive.
• Transmission is shifted out of park.
This automatic door lock function will only occur once per ignition cycle unless, a door jamb switch input changes state to active and back to inactive. Then the DDM, PDM and BCM will lock all doors again.
Once the automatic door lock feature has locked the doors, the BCM will then unlock all the doors when the transmission is shifted into park.
Driver, Passenger and Cargo Door Lock System Operation
The front power door lock switches are integral components of the driver door module (DDM) and passenger door module (PDM). The switches are two position normally open rocker switches. When placed in either the lock or unlock positions, the switches provide a direct input to the DDM or PDM. The DDM or PDM monitors these inputs and sends a Class 2 message indicating a change in the switch's respective position. Modules which activate the power door lock motors receive the Class 2 message and activate the motor in the appropriate direction to lock or unlock the vehicle's doors and liftgate. The rear door lock switch provides a lock and unlock signal to the body control module (BCM). The BCM upon receipt of a lock or unlock signal will control the rear door lock relays and also send a Class 2 message to the DDM and PDM to perform the appropriate function.
The modules which activate the power lock motors are:
• The DDM (driver door lock actuator).
• The PDM (passenger front door lock actuator).
• The BCM (both rear door lock actuators and cargo door/liftgate).
The DDM and PDM are directly connected to the respective door lock actuator through the door lock motor lock and unlock circuits. Once a door lock or unlock request has been received, the module will supply battery voltage to one side of the actuator and ground the other causing the doors to lock or unlock.
The rear passenger and cargo doors differ slightly in that they use lock and unlock relays. The relays supply and coil sides receive a constant voltage through the battery voltage supply circuit. The normally closed contacts are connected to ground and the control side is connected to the BCM. Once a door lock or unlock request has been received by the BCM, the BCM will ground the control side of the appropriate relay. This energizes the relay and allows voltage to be applied to either the door lock motor lock or unlock circuits. since the other side of the door lock actuator is connected to the normally closed contacts of the opposing relay to ground, the doors lock or unlock.

The lock actuator is weak in your case

I assume you mean that the central locking system will not lock the doors but you can do so manually.

Get inside the vehicle and close all doors.

On each rear door, lock and unlock the mechanism manually a couple of times. In other words do not use the key pad.

Then leave both rear doors in the locked position (manual locking) and operate the lock button on you key pad to operate the central locking system. Wait a few seconds then hit unlock on your key pad and a few seconds later hit lock on your key pad.

If the system fails to lock your rear doors you will need to get the vehicle to an auto electrician to check out the issue and rectify it for you. There are a number of possible causes which cannot be identified without physically checking the system. So you will need to have this rectified by a professional.

You mean that the central locking system will not lock the rear doors but you can do so manually.

Get inside the vehicle and close all doors.

On each rear door, lock and unlock the mechanism manually a couple of times. In other words do not use the key pad.

Then leave both rear doors in the locked position (manual locking) and operate the lock button on you key pad to operate the central locking system. Wait a few seconds then hit unlock on your key pad and a few seconds later hit lock on your key pad.

If the system fails to lock your rear doors you will need to get the vehicle to an auto electrician to check out the issue and rectify it for you. There are a number of possible causes which cannot be identified without physically checking the system. So you will need to have this rectified by a professional.

Sound like the door actuators are bad if you take it somewhere take it to a dealer auto body shop Its Cheaper

try punching the remote lock button twice. experience with 4 door s-blazers shows that it has to be done twice to lock all 4 doors. also look for "child safety" switched for the rear doors that may be disabling remote locking for the rears.

i work at a chevy dealership,just had the same problem my fix was to replace the power door lock relay located on drivers side interior fuse block

The rear doors have a separate relay for the lock and unlock function. There's a good chance the unlock relay is bad. The relays in question are located in the left instrument panel fuse block. Hope this helps