Liftgate wont close stuck in lock position

Power Liftgate System Components
• Liftgate motor assembly
• Liftgate latch
• Liftgate module (LGM)
• Liftgate side upper sensor - left
• Liftgate side upper sensor - right
• Liftgate handle switch
• Liftgate close switch
• GMLAN serial data link
• PWR LIFT GATE 30 amp fuse
• PLG 10 amp mini-fuse

Power Liftgate System Description
Liftgate Module
The liftgate module controls the liftgate motor, liftgate clutch, and liftgate latch based on various inputs. The liftgate module also performs diagnostics on these inputs and outputs and will disable liftgate functionality and set DTCs should a fault be detected. The liftgate module is secured to the motor assembly at the left rear of the vehicle. The module requires a liftgate position learn procedure be performed when replacing. This allows the module to learn the full open and full closed positions of the liftgate.

Location - fuse block right rear
Fuse Block - Right Rear
In the passenger compartment, near the right side of the rear seat cushion under the carpet

Door ajar switch possibly . The lift gate not working is a different matter . Could be any number of thing's .
Power Liftgate System Components
• Liftgate motor assembly
• Liftgate latch
• Liftgate module (LGM)
• Liftgate side upper sensor - left
• Liftgate side upper sensor - right
• Liftgate handle switch
• Liftgate close switch
• GMLAN serial data link
• PWR LIFT GATE 30 amp fuse
• PLG 10 amp mini-fuse

Your best bet take it to a qualified repair shop that has the diagnostic tool that can communicate with the lift gate control module , too check for DTC'S - diagnostic trouble code's .
Liftgate Module
The liftgate module controls the liftgate motor, liftgate clutch, and liftgate latch based on various inputs. The liftgate module also performs diagnostics on these inputs and outputs and will disable liftgate functionality and set DTCs should a fault be detected. The liftgate module is secured to the motor assembly at the left rear of the vehicle. The module requires a liftgate position learn procedure be performed when replacing. This allows the module to learn the full open and full closed positions of the liftgate.

DTC B153A 00: Liftgate Latch Switch Signal Circuit
DTC B153A 08: Liftgate Latch Switch Signal Circuit Signal Invalid
DTC B153B 02: Liftgate Open Switch Signal Circuit Short to Ground
DTC B153B 05: Liftgate Open Switch Signal Circuit Open
DTC B153E 02: Liftgate Position Sensor Signal Circuit Short to Ground
DTC B153E 05: Liftgate Position Sensor Signal Circuit Short to Battery or Open
DTC B153E 08: Liftgate Position Sensor Signal Circuit Signal Invalid

This is not a job for a diy'er or vehicle owner .

liftgate ajar switch , possibly . Without testing that would be just a guess . Do you know how to test automotive electrical circuit's ? Using a wiring diagram an a DVOM -digital volt ohm meter ? Looking at a factory service repair manual to find location of the ajar switch . Also checking for DTC- diagnostic trouble codes ,first !
B2703 Open/Close Switch Stuck Active Power Liftgate Module B2721 Gate Ajar Output Short to Ground or Open Power Liftgate Module REFER to Section 501-03 . B2722 Open/Close Switch Active During Self-Test Power Liftgate Module REFER to Section 501-03 .
B2718 Gate Ajar Output Short to Battery Power Liftgate Module REFER to Section 501-03 .

• The interior lights remain on and the instrument cluster message center indicates liftgate ajar

• Liftgate latch is not in primary position.

• Manually PULL on the liftgate. If liftgate moves, OPEN and CLOSE the liftgate to the primary latch position. Manually PULL on liftgate glass. If liftgate glass moves, OPEN and CLOSE the liftgate glass. If the liftgate ajar condition still exists, Go To Pinpoint Test B .

PINPOINT TEST B: THE POWER LIFTGATE DOES NOT OPERATE/DOES NOT OPERATE CORRECTLY Test Step Result / Action to Take B1 RETRIEVE THE DTCs FROM POWER LIFTGATE MODULE

• Use the recorded power liftgate module DTCs from the continuous and power liftgate module self-tests.
• Are any power liftgate module DTCs recorded?

Yes
If DTC B2552 or B2698, GO to B54 .

If DTC B2699 or B2701, GO to B40 .

If DTC B2700 or B2702, GO to B41 .

If DTC B2703 or 2722, GO to B4 .

If DTC B2704, B2705 or B2706, GO to B31 .

If DTC B2709, B2710, B2711, B2712, B2819, or B2820, GO to B23 .

If DTC B2713, GO to B19 .

If DTC B2714, B2715, B2821 or B2822, GO to B15 .

If DTC B2718 or B2721, GO to B46 .

If DTC B2723, GO to B50 .

If DTC B2724 or B2725, GO to B10 .

If DTC B2726, GO to B35 .

If DTC B2825, GO to Symptom Chart and verify symptom the power liftgate reverses during power close operation (mid-travel). If sent here from the symptom chart, GO to B23 .

If the liftgate unexpectedly reverses direction when ambient temperatures are greater than 32°C (90°F), GO to B23 .

No
GO to B2 .

Power Liftgate
The power liftgate feature will allow the customer to automatically OPEN or CLOSE the liftgate by activating the interior open/close switch, the remote keyless entry transmitter or by manually initiating liftgate movement. The power liftgate uses a power cinch system to latch the liftgate.
The power liftgate system consists of the following:

• Power liftgate control switch (located in the overhead console)
• Power liftgate motors (located in the rear headliner area)
• Optical sensor and power liftgate encoder wheel (located in the left power liftgate motor assembly)
• Pinch strip switches (located on the body by the liftgate)
• Home position switch (located on the cinch actuator)
• Forkbolt switch (located on the cinching latch assembly)
• Detent switch (located on the cinching latch assembly)
• Liftgate close chime module (located in a unit external from the power liftgate module)
• There are a lot of electrical switches an motors
• Visual Inspection Chart Mechanical Electrical
  • Power liftgate motors
  • Power cinching latch and linkage
  • Power liftgate pinch strip switches
  • Liftgate and liftgate hinges
  • Liftgate assist cylinders
  • Liftgate strikers
  • Exterior release handle and linkage
  • Liftgate weatherstrip
  • Liftgate alignment to body and striker
  • Central junction box (CJB) fuse:
    • 5 (7.5A)
    • 105 (30A)
  • Power liftgate control switch
  • Wiring harness
  • Connectors
  Are you willing to take the back hatch apart to test this ,to find a fix . But first have it check for DTC'S - diagnostic troulbe codes '
• Power Liftgate Module Diagnostic Trouble Code (DTC) Index
  Power Liftgate Module Diagnostic Trouble Code (DTC) Index DTC Description Source Action B1342 ECU Is Defective Power Liftgate Module INSTALL a new power liftgate module. REFER to Power Liftgate Module in this section. B2477 Module Configuration Failure Power Liftgate Module REFER to Section 418-01 . B2522 Vbatt1 Circuit Failure Power Liftgate Module Go To Pinpoint Test B . B2552 Vbatt2 Circuit Open Power Liftgate Module Go To Pinpoint Test B . B2698 Vbatt2 Circuit Failure Power Liftgate Module Go To Pinpoint Test B . B2699 Left Pinch Strip Open or Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2700 Right Pinch Strip Open or Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2701 Left Pinch Strip Stuck Active Power Liftgate Module Go To Pinpoint Test B . B2702 Right Pinch Strip Stuck Active Power Liftgate Module Go To Pinpoint Test B . B2703 Open/Close Switch Stuck Active Power Liftgate Module Go To Pinpoint Test B . B2704 Optical Sensor Power Short to Ground Power Liftgate Module Go To Pinpoint Test B . B2705 Optical Sensor 1 Input Not Active During Powered Gate Movement Power Liftgate Module Go To Pinpoint Test B . B2706 Optical Sensor 2 Input Not Active During Powered Gate Movement Power Liftgate Module Go To Pinpoint Test B . B2709 Gate Open Output Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2710 Gate Close Output Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2711 Gate Open Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2712 Gate Close Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2713 Unlatch Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2714 Uncinch Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2715 Cinch Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2718 Gate Ajar Output Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2721 Gate Ajar Output Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2722 Open/Close Switch Active During Self-Test Power Liftgate Module Go To Pinpoint Test B . B2723 Glass Position Switch Active During Self-Test Power Liftgate Module Go To Pinpoint Test B . B2724 Forkbolt Switch Invalid During Self-Test Power Liftgate Module Go To Pinpoint Test B . B2725 Detent Switch Invalid During Self-Test Power Liftgate Module Go To Pinpoint Test B . B2726 Home Switch Invalid During Self-Test Power Liftgate Module Go To Pinpoint Test B . B2819 Gate Motor Circuit Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2820 Gate Motor Circuit Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2821 Cincher Motor/Unlatch Actuator Short to Ground or Open Power Liftgate Module Go To Pinpoint Test B . B2822 Cincher Motor/Unlatch Actuator Short to Battery Power Liftgate Module Go To Pinpoint Test B . B2825 Movement Ceased Due to Excess Speed Deviation Power Liftgate Module Go To Pinpoint Test B . B2903 Chime Output Circuit Short to Battery Power Liftgate Module/ Liftgate Chime Module Go To Pinpoint Test C . C1935 Chime Circuit Failure Power Liftgate Module/ Liftgate Chime Module Go To Pinpoint Test C . U1950 UBP Communication BUS Fault UBP Communi- cation REFER to Section 418-00 . U2338 Invalid ACM Message Data Power Liftgate Module REFER to Section 418-00 . U2242 Invalid 4WAS Message Data 4WAS Module REFER to Section 308-07A . U2403 Invalid CSM Message Data Vehicle Security Module REFER to Section 418-00 . U2406 Invalid IC Message Data Instrument Cluster Module REFER to Section 413-01 . U2469 Power Liftgate Disabled By Customer Interface Instrument Cluster Module Turn power liftgate on at message center. U2470 Unexpected Keyfob/Keypad Button Press Power Liftgate Module Go To Pinpoint Test A . U2471 Unexpected PRNDL State Power Liftgate Module REFER to Section 419-10 . U2472 Unexpected IGN State Power Liftgate Module REFER to Section 418-00 . U2473 Unexpected Vehicle Speed Instrument Cluster Module/ Powertrain Control Module REFER to Section 413-01 . U2528 PRNDL Data Mismatch Power Liftgate Module/ Instrument Cluster Module Go To Pinpoint Test D .

I have a 2008 Suburban with the power liftgate disabled. I have had the power latch stop working, and the BCM report that the rear access open when it is closed (both gate and glass). Somehow the liftgate module thinks the gate is open, so I cannot open the gate at all, and the latch and rear wiper will not work. To reset the control module I pulled the liftgate fuse (#20) in the instrument panel fuse box, turned the car on, off, reinstalled fuse, turned car on, unlocked doors using drivers side switch, and the power latch will function again - at least for a while.

no answer but same problem. ever figure it out?

spray the latch down with starting fluid to remove grease then spray it with silicone to lubricate as grease will bid up lock lever worked for me

try climbing inside toward the lift gate and feel for a emergency release mechanism, and try the remote lock release

The easy part is you just need the latch for the liftgate. The hard part is getting to it and opening the liftgate to replace the latch. You should be able to pull the liftgate trim off most of the way with the gate closed and try to manually actuate the latch to open the gate. You may have to go so far as breaking the latch from the inside to open the gate and then replace your latch.