Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2018TAHOE LT, 4WD, GASREPAIR AND DIAGNOSISBODY & FRAMEWINDOWSFIXED AND MOVEABLE WINDOW SYSTEMDIAGNOSTIC INFORMATION AND PROCEDURESLIFTGATE WINDOW RELEASE INOPERATIVECIRCUIT/SYSTEM TESTING
2018 Chevrolet Tahoe LT, 4WD, Gas
Circuit/System Testing
2018 Chevrolet Tahoe LT, 4WD, GasSECTION Circuit/System Testing
Liftgate Window Switch Inoperative
- Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S141 Liftgate Window Unlatch Switch. It may take up to 2 minutes for all vehicle systems to power down.
- Test for less than 10 Ω between the ground circuit terminal 1 and ground.
- If 10 Ω or greater
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
- Ignition ON.
- Verify the scan tool Exterior Liftgate Window Unlatch Switch parameter is Inactive.
- If not Inactive
- Ignition OFF, disconnect the harness connector at the K9 Body Control Module.
- Test for infinite resistance between the signal circuit terminal 2 and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance, replace the K9 Body Control Module.
- Go to next step: If Inactive
- Install a 3 A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1.
- Verify the scan tool Exterior Liftgate Window Unlatch Switch parameter is Active.
- If not Active
- Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the K9 Body Control Module, ignition ON.
- Test for less than 1 V between the signal circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V
- Test for less than 2 Ω in the signal circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- Go to next step: If Active
- Test or replace the S141 Liftgate Window Unlatch Switch.
Liftgate Window Latch Inoperative
- Ignition OFF and all vehicle systems OFF, disconnect the KR162 Liftgate Window Unlatch Relay. It may take up to 2 min for all vehicle systems to power down.
- Test for less than 10 Ω between the ground circuit terminal 16 and ground.
- If 10 Ω or greater
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
- Ignition ON.
- Verify a test lamp illuminates between the B+ circuit terminal 7 and ground.
- If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF.
- Test for less than 2 Ω in the B+ circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF.
- Test for infinite resistance between the B+ circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Disconnect the harness connector at the M33 Liftgate Window Latch Assembly.
- Test for infinite resistance between the control circuit terminal 15 and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance, replace the Liftgate Window Unlatch Relay.
- Go to next step: If the test lamp illuminates
- Connect a test lamp between the control circuit terminal 6 and the ground circuit terminal 16.
- Verify the test lamp turns ON and OFF when pressing and releasing the S141 Liftgate Window Unlatch Switch.
- If the test lamp is always OFF
- Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
- Test for infinite resistance between the control circuit and ground.
- If less than infinite resistance, repair the short to ground on the circuit.
- If infinite resistance
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the K9 Body Control Module.
- If the test lamp is always ON
- Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
- Test for less than 1 V between the control circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the K9 Body Control Module.
- Go to next step: If the test lamp turns ON and OFF
- Verify that a test lamp does not illuminate between the control circuit terminal 15 and ground.
- If the test lamp illuminates
Repair the short to voltage on the control circuit
- Go to next step: If the test lamp does not illuminate
- If the test lamp illuminates
- Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the M33 Liftgate Window Latch Assembly. It may take up to 2 min for all vehicle systems to power down.
- Test for less than 10 Ω between the ground circuit terminal 2 and ground.
- If 10 Ω or greater
- Ignition OFF.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 Ω
- Connect the harness connector at the M33 Liftgate Window Latch Assembly.
- Ignition ON, connect a 10 A fused jumper wire between the B+ circuit terminal 7 and the control circuit terminal 15.
- Verify the M33 Liftgate Window Latch Assembly is activated.
- If the M33 Liftgate Window Latch Assembly does not activate
- Ignition OFF, remove the jumper wire, disconnect the harness connector at the M33 Liftgate Window Latch Assembly.
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the M33 Liftgate Window Latch Assembly.
- Go to next step: If the M33 Liftgate Window Latch Assembly activates
- Test or replace the KR162 Liftgate Window Unlatch Relay.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.