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 MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 63 (FIXED AND MOVEABLE WINDOW SYSTEM)DIAGNOSTIC INFORMATION AND PROCEDURESPOWER WINDOWS MALFUNCTIONCIRCUIT/SYSTEM DESCRIPTION
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol
Circuit/System Description
2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Description
WARNING: This page is about a different car, the 2018 Chevrolet Sonic. However, it is still accessible from the selected car via links, so may be relevant.
For an overview of the component/system, refer to: Power Windows Description and Operation
| Circuit | Description |
|---|---|
| B+ - M74D Window Motor - Driver | Supplied from a fuse. |
| B+ - M74P Window Motor - Passenger | Supplied from a fuse. |
| B+ - S79LR Window Switch - Left Rear | Supplied from a fuse. |
| B+ - S79RR Window Switch - Right Rear | Supplied from a fuse. |
| Signal - Down @ M74D Window Motor - Driver | The output circuit is switched to ground to activate the component. |
| Signal - Up @ M74D Window Motor - Driver | The output circuit is switched to ground to activate the component. |
| Signal - Express @ M74D Window Motor - Driver | The output circuit is switched to ground to activate the component. |
| Signal - Up @ M74P Window Motor - Passenger | The output circuit is switched to ground to activate the component. |
| Signal - Down @ M74P Window Motor - Passenger | The output circuit is switched to ground to activate the component. |
| Signal - Express @ M74P Window Motor - Passenger | The output circuit is switched to ground to activate the component. |
| Control - Up @ M74LR Window Motor - Left Rear | The output circuit is switched from ground to 12 V to activate the component. |
| Control - Down @ M74LR Window Motor - Left Rear | The output circuit is switched from ground to 12 V to activate the component. |
| Control - Up @ M74RR Window Motor - Right Rear | The output circuit is switched from ground to 12 V to activate the component. |
| Control - Down @ M74RR Window Motor - Right Rear | The output circuit is switched from ground to 12 V to activate the component. |
| Ground | Chassis Ground |
| Component | Description |
|---|---|
| S79D Window Switch - Driver | The S79D sends a serial data message to the K9 indicating the M74 function that has been requested. |
| M74D Window Motor - Driver |
|
| S79P Window Switch - Passenger | The switch has a normally open contact. |
| M74P Window Motor - Passenger |
|
| S79LR Window Switch - Left Rear | The switch has a normally open contact. |
| M74LR Window Motor - Left Rear | An electric DC motor. |
| S79RR Window Switch - Right Rear | The switch has a normally open contact. |
| M74RR Window Motor - Right Rear | An electric DC motor. |
| K9 Body Control Module | The module controls various vehicle functions like lighting, central door locking, power windows, etc. |
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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.