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 MANUALSCHEVROLET2020EXPRESS 2500 LS, 2.8L ENG VIN 1REPAIR AND DIAGNOSISBODY & FRAMEFIXED AND MOVEABLE WINDOWSDIAGNOSTIC INFORMATION AND PROCEDURESPOWER WINDOWS MALFUNCTIONCIRCUIT/SYSTEM DESCRIPTION
2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1
Circuit/System Description
2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1SECTION Circuit/System Description
For an overview of the component/system, refer to:Power Windows Description and Operation
| Circuit | Description |
|---|---|
| Ignition | Supplied from a fuse. |
| Control - Down @ M74 Window Motor | The output circuit is switched from ground to 12 V to activate the component. |
| Control - Up @ M74 Window Motor | The output circuit is switched from ground to 12 V to activate the component. |
| Ground | Chassis Ground |
| Component | Description |
|---|---|
| S79 Window Switch | The assembly on the driver side has one switch for the driver window and one switch for the passenger window. Each switch has 2 outputs, one for window down and one for window up. The motors contain electronics that interpret the up/down signals and actuate the motors accordingly. The circuits for the motor in the driver door are directly wired to the motor. The circuits for the window in the passenger door first go to the passenger window switch and then to the motor. In the inactive position the switch on the passenger side passes on the two control signals as they are. When actuated, it switches one of the control circuits to 12 V. |
| M74 Window Motor | The motor M74 is a bidirectional DC motor that moves the component: Front Power Windows |
RENDER: 1.0x
NO RELATED
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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.