The computer BCM and PCM and sensors are responsible for readout.... Check your car battery and charging system first. Computers work on voltage data and senor input. Low or unsteady voltage can effect input and output information and the computers timely control of several automobile functions. It can be problematic at night as headlights pull alot of voltage.
It could be the wire or possibly the module itself. Access the module, remove the connector, and check for power on the gray wire terminal when the key and switch is on. No power, repair the wire. If there is power, replace the wiper module.
Take the liftgate inside panel off an check the wiring , connections etc....
rear door hatch lock repair GMC Chevroletchevy 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
The complexity of the electronics on this vehicle , electronic throttle control ,
The throttle actuator control (TAC) module is the control center for the throttle actuator control system. The TAC system is self-diagnosing and provides diagnostic information to the powertrain control module (PCM) through a dedicated serial data line. The TAC achieves throttle positioning by providing a pulse width modulated voltage to the TAC, as directed by the PCM.
The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. The serial data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable pulse width modulation to carry data and depending on the message it may operate faster or slower. The bus will float at a nominal 7 volts during normal operation. Each module can pull this lower during the transmission. The bus is not at battery positive voltage or ground potential during normal operation. When the ignition switch is in RUN, each module communicating on the class 2 serial data line sends a state of health (SOH) message every 2 seconds to ensure that the module is operating properly. When a module stops communicating on the class 2 serial data line, for example if the module loses power or ground, the SOH message it normally sends on the data line every 2 seconds disappears. Other modules on the class 2 serial data line, which expect to receive that SOH message, detect its absence; those modules in turn set an internal DTC associated with the loss of SOH of the non-communicating module. The DTC is unique to the module which is not communicating, for example, when the inflatable restraint sensing and diagnostic module (SDM) SOH message disappears, several modules set DTC U1088. Note that a loss of serial data DTC does not normally represent a failure of the module that set it.
Your best bet is take it where they have the electronic test equipment to check this problem out.
It is located behind the right rear quarter panel , In the back right of the interior !
Remove the right rear quarter trim panel. Refer to Rear Quarter Trim Panel Replacement - Right Side in Interior Trim.
Removal Procedure
Remove the rear seat. Refer to Rear Number 2 Seat Replacement or Rear Number 2 50-50 Seat Replacement in Seats.
Remove the Third Pillar trim panel. Refer to Third Pillar Trim Replacement .
Remove the garnish molding. Refer to Body Rear Corner Garnish Molding Replacement .
Remove the door sill plate. Refer to Liftgate Door Sill Plate Replacement .
Remove the quarter panel trim screws.
A lot involved in this but not to difficult !
Remove the rear door sill trim plate. Refer to Front Side Door Sill Plate Replacement or to Rear Side Door Sill Plate Replacement .
Remove the lower rear seat belt cover and bolt.
Remove the trim panel from the vehicle.
Remove the sill plate. Firmly pull the sill plate up and out from the retainers.
Remove the sill plate from the vehicle. Start from the front of the door sill. Use a flat-bladed tool in order to pry the door sill plate.
Rear Side Door Sill Trim Plate Replacement
Use a flat-bladed tool in order to pry the door sill plate. Remove the sill plate from the vehicle.
Body Rear Corner Garnish Molding Replacement
Remove the rear upper garnish molding. Refer to Rear Upper Garnish Molding Replacement .
Pull down on the upper corners of the garnish molding in order to disengage the retaining clips. Pull in order to disengage the remaining retaining clips. Remove the rear corner garnish molding from the vehicle. Inspect the rear corner garnish molding for broken or missing retaining clips. Replace the retaining clips as needed.
Good Luck ! Fun job !!!!!
Ensure that coolant mixture is correct, that air has been bled from
cooling system. Check that water temp is okay and fan cutting
when it should. If all is okay have the idle checked.
Did you try jump starting the vehicle?
If you left the key on all the accessory functions where on and this will cause the battery to go dead overnight. Jump starting to see if the vehicle will start is a good way to determine if the battery did go dead. Depending on how old the battery is it may have gone bad by letting it go dead overnight. If its more than a few years old it may not be a bad idea to just replace it. I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa
Back to basics, as things fail while just sitting still sometimes. Getting spark to plugs? Correct fuel pressure? Will small spray of starter fluid make it start for a few seconds?
