2005 Tahoe Rear liftgate will not open. Power lock open all other doors. Does not have a key spot to open manually

The rear hatch locking is computer contolled .
The BCM also runs diagnostics on the liftgate lock relay control circuit and will set DTC B3825 as current and also send a Class 2 message to the DIC. The DIC will display REPLACE LIFTGATE FUSE to inform the driver that a fault has been detected in the liftgate lock circuit and that the liftgate is not locked. Faults that will set the DTC and cause the DIC to display the message could be any of the following:
• An open ECC fuse
• An open or short to ground in the liftgate lock relay battery positive voltage circuit
• A faulty liftgate lock relay
• An open or short to ground in the liftgate lock relay control circuit
• A short to ground in the liftgate lock actuator lock control circuit
• A faulty BCM

The liftgate lock relay supply and coil sides receive a constant voltage through the battery voltage supply circuit and the ECC fuse. The normally closed contact is connected to ground and the control side is connected to the body control module (BCM). A lock function will occur when a door lock switch activation, keyless entry lock transmission, auto door lock function or a liftgate lock function has been received by the BCM. The BCM will then ground the control side of the liftgate lock relay. This energizes the relay and allows voltage to be applied to the liftgate lock actuator lock control circuit. Since the other side of the liftgate lock actuator is connected to the normally closed contacts of the door unlock relay to ground, the liftgate will lock. When an unlock function occurs the BCM will ground the control side of the unlock relay and the rear doors and liftgate will unlock.
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)

If i were to guess i would say you mite need a new lock actuator , but i don't guess . You could take the hatch inside panel off an check for B+ voltage for the lock actuation as someone pushes the switch . Or have it checked for codes .

first is diagnosis.
you examine and test it. to see if its electrical or mech. failure.
and once discovered that follow that to logical conclusions.

There is a known TSB for this....
#07-08-52-003: Rear Liftgate Glass May Not Lock When Using Remote Keyless Entry (RKE)/Key Fob Transmitter/Door Lock Switch, Lifgtate Hatch or Liftgate Glass May Lock/Unlock When Rear Liftgate Glass Button Depressed - (Sep 13, 2007)


Subject: Rear Liftgate Glass May Not Lock When Using Remote Keyless Entry (RKE), Key Fob Transmitter or Door Lock Switch, And/Or Liftgate Hatch Or Liftgate Glass May Lock Then Unlock When Rear Liftgate Glass Button is Depressed (Reposition Lock Cylinder Wave Washer and Adjust Lock Rod)


Models: 2005-2007 Buick Rainier

2005-2008 Chevrolet TrailBlazer, TrailBlazer EXT, TrailBlazer SS

2005-2008 GMC Envoy, Envoy XL, Envoy Denali

2005-2008 Saab 9-7X




--------------------------------------------------------------------------------
Do This
Don't Do This

Reposition liftgate lock cylinder wave washer and adjust lock rod.
DO NOT replace the liftgate latch or actuator.


Condition
Some customers may comment on one or more of the following conditions:

• The rear liftgate glass may not lock when using the remote keyless entry (RKE), key fob transmitter or door lock switch unless the lock is pressed a second time.

• The rear liftgate or glass locks, but may be unlocked when the rear liftgate lock cylinder button is depressed.

• The rear liftgate locks but the liftgate glass may not lock.

Cause
These conditions may be caused by one or all of the following:

• The rear liftgate cylinder lock rod may be out of adjustment.





• The wave washer on the liftgate lock cylinder may be out of position with the cup side down.

• Excessive movement or slack in the lock rods at the liftgate bell crank assembly.





• The liftgate lock cylinder pawl may contact the rear liftgate glass latch when the lock cylinder button is depressed.

Correction
Important: Do Not remove the rear liftgate lock cylinder from the vehicle to perform this repair.

Reposition the rear liftgate lock cylinder wave washer and adjust the lock rod using the steps below.

Verify the customer's condition.

Open the liftgate.

Remove the upper liftgate garnish molding.

Remove the rear liftgate trim panel.

Remove the cylinder lock rod from the threaded lock rod retaining clip.

Tip
Place the tip of a screwdriver blade into the opening of the C-clip and slowly rotate the screwdriver to pry out the C-clip from the shaft. Then use needle-nose pliers to remove the C-clip.

Remove the C-clip from the rear liftgate lock cylinder push button and remove the wave washer.

Install the wave washer with the cup side up.

Position the wave washer with the curved edges of the wave spring parallel to the tabs on the lock cylinder shaft.

Important: Use needle-nose pliers to slightly squeeze the C-clip back into shape. Make sure the clip seated, you should feel a snap and hear an audible click.

Install the C-clip onto the shaft and in the slot using needle nose pliers. Then rotate the pawl several times to make sure the C-clip does not rotate. If the clip rotates then the clip is not fully seated.

Position the lock cylinder pawl to the full clockwise position.

Pull up on the cylinder lock rod to remove any slack in the bell crank.

Install the cylinder lock rod into the threaded lock rod retaining clip while removing any slack from the lock rod linkage.

Close the lock rod retainer clip.

Close the liftgate assembly.

Open the liftgate glass while keeping the liftgate closed.

Use the key fob to cycle the liftgate to the lock and unlock position while inspecting the rear liftgate pawl. The lock cylinder pawl should have clearance between the latch as shown above. If the pawl is contacting the latch, readjust the cylinder lock rod.

Verify that the customer's condition has been corrected.

Install the rear liftgate trim panel.

Install the upper liftgate garnish molding.

#07-08-52-003: Rear Liftgate Glass May Not Lock When Using Remote Keyless Entry (RKE)/Key Fob Transmitter/Door Lock Switch, Lifgtate Hatch or Liftgate Glass May Lock/Unlock When Rear Liftgate Glass Button Depressed - (Sep 13, 2007)


Subject: Rear Liftgate Glass May Not Lock When Using Remote Keyless Entry (RKE), Key Fob Transmitter or Door Lock Switch, And/Or Liftgate Hatch Or Liftgate Glass May Lock Then Unlock When Rear Liftgate Glass Button is Depressed (Reposition Lock Cylinder Wave Washer and Adjust Lock Rod)


Models: 2005-2007 Buick Rainier

2005-2008 Chevrolet TrailBlazer, TrailBlazer EXT, TrailBlazer SS

2005-2008 GMC Envoy, Envoy XL, Envoy Denali

2005-2008 Saab 9-7X




--------------------------------------------------------------------------------
Do This
Don't Do This

Reposition liftgate lock cylinder wave washer and adjust lock rod.
DO NOT replace the liftgate latch or actuator.


Condition
Some customers may comment on one or more of the following conditions:

• The rear liftgate glass may not lock when using the remote keyless entry (RKE), key fob transmitter or door lock switch unless the lock is pressed a second time.

• The rear liftgate or glass locks, but may be unlocked when the rear liftgate lock cylinder button is depressed.

• The rear liftgate locks but the liftgate glass may not lock.

Cause
These conditions may be caused by one or all of the following:

• The rear liftgate cylinder lock rod may be out of adjustment.





• The wave washer on the liftgate lock cylinder may be out of position with the cup side down.

• Excessive movement or slack in the lock rods at the liftgate bell crank assembly.





• The liftgate lock cylinder pawl may contact the rear liftgate glass latch when the lock cylinder button is depressed.

Correction
Important: Do Not remove the rear liftgate lock cylinder from the vehicle to perform this repair.

Reposition the rear liftgate lock cylinder wave washer and adjust the lock rod using the steps below.

Verify the customer's condition.

Open the liftgate.

Remove the upper liftgate garnish molding.

Remove the rear liftgate trim panel.

Remove the cylinder lock rod from the threaded lock rod retaining clip.

Tip
Place the tip of a screwdriver blade into the opening of the C-clip and slowly rotate the screwdriver to pry out the C-clip from the shaft. Then use needle-nose pliers to remove the C-clip.

Remove the C-clip from the rear liftgate lock cylinder push button and remove the wave washer.

Install the wave washer with the cup side up.

Position the wave washer with the curved edges of the wave spring parallel to the tabs on the lock cylinder shaft.

Important: Use needle-nose pliers to slightly squeeze the C-clip back into shape. Make sure the clip seated, you should feel a snap and hear an audible click.

Install the C-clip onto the shaft and in the slot using needle nose pliers. Then rotate the pawl several times to make sure the C-clip does not rotate. If the clip rotates then the clip is not fully seated.

Position the lock cylinder pawl to the full clockwise position.

Pull up on the cylinder lock rod to remove any slack in the bell crank.

Install the cylinder lock rod into the threaded lock rod retaining clip while removing any slack from the lock rod linkage.

Close the lock rod retainer clip.

Close the liftgate assembly.

Open the liftgate glass while keeping the liftgate closed.

Use the key fob to cycle the liftgate to the lock and unlock position while inspecting the rear liftgate pawl. The lock cylinder pawl should have clearance between the latch as shown above. If the pawl is contacting the latch, readjust the cylinder lock rod.

Verify that the customer's condition has been corrected.

Install the rear liftgate trim panel.

Install the upper liftgate garnish molding.

the liftgate relay it is located on the "B" pillar passenger side This is the door post between front and rear seats. if the fuse is good listen/feel this area for the relay clicking.

To unlock the liftgate, press the unlock button on the Remote Keyless Entry (RKE) transmitter twice or use the power door lock switch.
To lock the liftgate, press the lock button on the RKE transmitter or use the power door lock switch. The liftgate does not have a key lock cylinder.
To open the liftgate, pull up on the handle located in the center of the liftgate.
When closing the liftgate, use the molded handles to pull the liftgate down. Push the liftgate closed until it latches.

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Take the liftgate inside panel off an check the wiring , connections etc....
rear door hatch lock repair GMC Chevrolet
chevy tahoe lift gate not opening
The liftgate will lock any time the vehicle is shifted out of park on vehicles equipped with an automatic transmission and at vehicle speeds exceeding 5 kph with manual transmission. This happens in conjunction with auto door locks if enabled or independently of auto door locks if the feature is disabled. This ensures that the liftgate is locked anytime the vehicle is shifted out of park or when the vehicle is in motion.
The liftgate lock relay supply and coil sides receive a constant voltage through the battery voltage supply circuit and the ECC fuse. The normally closed contact is connected to ground and the control side is connected to the body control module (BCM). A lock function will occur when a door lock switch activation, keyless entry lock transmission, auto door lock function or a liftgate lock function has been received by the BCM. The BCM will then ground the control side of the liftgate lock relay. This energizes the relay and allows voltage to be applied to the liftgate lock actuator lock control circuit. Since the other side of the liftgate lock actuator is connected to the normally closed contacts of the door unlock relay to ground, the liftgate will lock. When an unlock function occurs the BCM will ground the control side of the unlock relay and the rear doors and liftgate will unlock.
The BCM also runs diagnostics on the liftgate lock relay control circuit and will set DTC B3825 as current and also send a Class 2 message to the DIC. The DIC will display REPLACE LIFTGATE FUSE to inform the driver that a fault has been detected in the liftgate lock circuit and that the liftgate is not locked. Faults that will set the DTC and cause the DIC to display the message could be any of the following

Power Door Locks Inoperative - Endgate/Liftgate

Schematic Reference: Door Lock/Indicator Schematics
Connector End View Reference: Power Door Systems Connector End Views
1
Did you perform the Diagnostic System Check - Vehicle?
YES - Go to Step 2
NO - Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2
Activate the door lock switches to the lock and unlock positions.
Do both rear passenger doors lock and unlock?
YES - Go to Step 3
NO - Go to Power Door Locks Inoperative
3
Did the liftgate lock actuator lock and unlock?
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 4
4
Disconnect liftgate door lock actuator.
With a test lamp connected to a good ground, probe the door lock actuator lock circuit at the door lock actuator harness connector.
Activate a door lock switch to lock position.
Does the test lamp illuminate?
YES - Go to Step 5
NO - Go to Step 7
5
With a test lamp connected to a good ground, probe the door lock actuator unlock circuit at the door lock actuator harness connector.
Activate a door lock switch to unlock position.
Does the test lamp illuminate?
YES - Go to Step 6
NO - Go to Step 8
6
Inspect for poor connections at the harness connector of the door lock actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 10
NO .. Go to Step 9
7
Repair the open door lock actuator lock circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 10
--
8
Repair the open in the door lock actuator unlock circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
Go to Step 10
--
9
Replace the liftgate door lock actuator. Refer to Door Lock Actuator Replacement in Body Rear End.
Did you complete the repair?
Go to Step 10
--
10
Operate the system in order to verify the repair.
Did you correct the condition?
System OK
Go to Step 2