Cargo doors will not lock or unlock - 1998 Chevrolet Tahoe

The most likely culprit is a faulty actuator. You can test this by having someone activate the rear hatch while listening for a click or sound of some sort. If there is sound but no opening, it indicates a bad latch actuator. If there is no noise, it could be a fuse or wiring issue. You can manually unlock the door by removing the trim, but be careful around the glass latch as there are 2 push pins.

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Check the wiring in the boot that runs from the body to the top of the liftgate for broken wires.

You might have to take it to a collision shop. Remove the rear hatch panel to gain access to the latch assembly if it's not responding. If you can't get it open, take it to a collision shop as they deal with these kinds of things regularly.

Service repair info. manual would be the place to start ,seeing how you have no clue .,or maybe a qualified repair shop. How are you going to fix it with out knowledge of how it works an what to check , --------------------------------------------------------------------------------
Power Door Locks Circuit Description
The power door locks are operated by reversible motors. The motors are found in the following locations:
• In each front door
• The side door
• The rear door
The PWR ACCY circuit breaker (30A) supplies voltage to the door lock motors.
If you move either power door lock switch, mounted in the front doors, the LOCK applies voltage to cavity F of the door lock relay. This energizes the lock coil in the relay. Current then flows through CKT 295 (GRY) directly to the following components:
• Both front door lock motors
• The side door lock motor
• The rear door lock motor (cargo doors only)
CKT 246/294 (TAN) provides the ground for the motors. The normally closed contacts of the UNLOCK then contacts the door lock relay.
If you move one of the door lock switches to UNLOCK the polarity of the system reverses. Current flows through the energized UNLOCK relay contacts. The LOCK relay contacts provide ground.
When the UNLOCK button is pressed once on the RKE transmitter, only the driver door unlocks. If it is pressed a second time within 5 seconds, all doors unlock.
If the side door is open, the side door jamb switch ground signal is opened/broken. If you move the door lock switch to LOCK while the side door is open, the following actions occur:
• The 2 front doors lock
• The rear door locks (cargo doors only)
When you close the side door, the door jamb switch closes. This closes the ground signal to the body control module {CKT 775 (PNK)}. A 5 second timer then starts in the module. After 5 seconds, cavity A4 connector C1 of the body control module supplies voltage to the door lock relay via CKT 195 (LT BLU). This energizes the door lock relay, which sends voltage to the door lock motors in order to lock the side door. Refer to Door Jamb Switches, Liftgate Strut Switch for a schematic of all door jamb switch inputs.
If the side door opens during this 5 seconds, the 5 seconds timer is reset. The locking pulse takes place at the end of the 5 seconds. Unlocking the door resets the 5 second timer in the body control module.
Use the following components in order to unlock the door lock system:
• The LH power door lock switch
• The RH power door lock switch
On vehicles equipped with cargo doors, the cargo door opener mechanically opens the door once the door lock system is unlocked. On vehicle equipped with a liftgate, the liftgate lock/unlock release switch (mechanical key) is added in order to serve the same function as the front power door lock switches. These functions locking and unlocking all doors, including the liftgate. Once the door lock system is unlocked, press the liftgate release switch in order to electrically open the liftgate and pull the handle in order to open the secondary latch.

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.

Power Door Locks Circuit Description
The power door lock system incorporates door lock switches on both front doors and on the RH D-pillar, door lock motors in all passenger doors and in the RR cargo door, a door lock relay and a door lock control module.
Power for the door lock switches and the door lock control module is supplied from the CIG LTR fuse 13 through CKT 640 (ORN). Power for the door lock relay is supplied from the PWR ACCY circuit breaker through CKT 540 (ORN). Ground for the door lock relay is supplied from G202 through CKT 150 (BLK) and ground for the door lock control module is supplied from G400 through CKT 150 (BLK).
The door lock motors are reversible and both sides are connected to the normally closed contacts of the door lock relay. Those contacts of the relay are connected to G202. When any of the door lock switches are placed in the lock position, voltage is supplied through CKT 195 (LT BLU) to the relay lock coil. Since the other side of the lock coil is connected to ground, the coil is energized and it pulls the lock contacts closed. Voltage is then supplied through CKT 295 (GRY) to all the door lock motors and the doors lock. The unlock function operates in much the same manner except that when any of the switches are placed in the unlock position, voltage is supplied through CKT 194 (WHT) to the unlock coil of the relay and CKT 294 (TAN) supplies voltage to the apposite side of the door lock motor and the doors unlock.
Door Lock Control Module Description
The door lock control module is used on vehicles equipped with cargo doors. The purpose of the module is to lock the cargo doors after a lock cycle has been commanded from any of the door lock switches with the cargo doors open. When the RH cargo door is open, the module receives a ground signal from the closed contacts of the rear door jamb switch on CKT 1897 (ORN/BLK) to G400. When a lock command is received, the module retains this input until it receives an open input from the rear door jamb switch. Then the module sends a lock command through CKT 194 (WHT) to the door lock relay and the doors lock.
Rear Cargo Doors Description
The power door lock motor will not operate unless the rear cargo doors are fully closed. The power door lock motor is in the right cargo door. The contactors are on the rear cargo door opening on the body and on the right cargo door.

the electric door lock button should unlock the rear lift gate.

U will have to open th door from th in side. To unlock it. Remove the inside panel. And where th key go, u can unlocked from th inside. But firs try to lock and unlock th door whit th electric control while u try to open th door. Because sometimes they are just stock and need lubrication. Good lock

be sure all mechanical parts of lock are lubed and free to move lock catches could be to close to each other making it to hard for the actuator to pull

There is a flash for the body control module for this problem. You need to go to the dealership to get it performed though.

how do you removed the interior cover? for the rear door actuator?

your lock acuteuator is stuck replace it and you should be fine