Safety Warning

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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 TESTING

2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1

Circuit/System Testing

2020 Chevrolet Express 2500 LS, 2.8L Eng VIN 1SECTION Circuit/System Testing

Test 1

NOTE:

It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

Ignition/Vehicle & All vehicle systems - Off
Disconnect the electrical connector: S79D Window Switch - Driver
Test for less than 10 ohms between the test points:Ground circuit terminal F & Ground
- If 10 ohms or greater
1. Ground Connection - Disconnect
2. Test for less than 2 ohms between the test points:Ground circuit terminal F @ Component harness & Ground Connection
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Repair the open/high resistance in the ground connection.
- Go to next step: If less than 10 ohms
Ignition - On / Vehicle - In Service Mode
Verify a test lamp turns On between the test points: Ignition circuit terminal C & Ground
- If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Test for less than 2 ohms between the test points:Ignition circuit terminal C & Output terminal @ CB2PA Fuse
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not turn On and the circuit fuse is open
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Test for infinite resistance between the test points:Ignition circuit terminal C & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
3. Test for infinite resistance between the test points:
  - Control circuit terminal A & Ground
  - Control circuit terminal D & Ground
  - Control circuit terminal G & Ground
  - Control circuit terminal H & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - If infinite resistance - Test or replace the component: S79D Window Switch - Driver
- Go to next step: If the test lamp turns On
Ignition/Vehicle - Off
Connect the electrical connector: S79D Window Switch - Driver
Disconnect the electrical connector: M74D Window Motor - Driver
Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2
Ignition - On / Vehicle - In Service Mode
Operate the component: S79D Window Switch - Driver
Verify the test lamp state:
- Not Used = Test lamp Off
- S79D Window Switch - Driver - Pulled = Test lamp On
- S79D Window Switch - Driver - Pressed = Test lamp On
- If not the specified state
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector: S79D Window Switch - Driver
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for infinite resistance between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
7. Test for less than 2 ohms between the test points:
  - Control circuit terminal 1 @ Component harness & Terminal H @ S79D Window Switch - Driver
  - Control circuit terminal 2 @ Component harness & Terminal G @ S79D Window Switch - Driver
    - If 2 ohms or greater - Repair the open/high resistance in the circuit.
    - If less than 2 ohms - Replace the component: S79D Window Switch - Driver
- Go to next step: If the specified state
Test or replace the component: M74D Window Motor - Driver

Test 2

Ignition/Vehicle - Off
Disconnect the electrical connector: S79P Window Switch - Passenger
Connect a test lamp between the test points: Control circuit terminal D & Control circuit terminal H
Ignition - On / Vehicle - In Service Mode
Operate the component:Passenger Window Switch @ S79D Window Switch - Driver
Verify the test lamp state:
- Not Used = Test lamp Off
- Passenger Window Switch - Pulled = Test lamp On
- Passenger Window Switch - Pressed = Test lamp On
- If not the specified state
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector: S79D Window Switch - Driver
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points:
  - Control circuit terminal D @ Component harness & Ground
  - Control circuit terminal H @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for infinite resistance between the test points:
  - Control circuit terminal D @ Component harness & Ground
  - Control circuit terminal H @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
7. Test for less than 2 ohms between the test points:
  - Control circuit terminal D @ Component harness & Terminal D @ S79D Window Switch - Driver
  - Control circuit terminal H @ Component harness & Terminal A @ S79D Window Switch - Driver
    - If 2 ohms or greater - Repair the open/high resistance in the circuit.
    - If less than 2 ohms - Replace the component: S79D Window Switch - Driver
Ignition/Vehicle - Off
Connect the electrical connector: S79P Window Switch - Passenger
Disconnect the electrical connector: M74P Window Motor - Passenger
Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2
Ignition - On / Vehicle - In Service Mode
Operate the component:Passenger Window Switch @ S79D Window Switch - Driver
Verify the test lamp state:
- Not Used = Test lamp Off
- Passenger Window Switch - Pulled = Test lamp On
- Passenger Window Switch - Pressed = Test lamp On
- If not the specified state
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Disconnect the electrical connector: S79P Window Switch - Passenger
3. Ignition - On / Vehicle - In Service Mode
4. Test for less than 1 V between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ Component harness & Ground
  - If 1 V or greater - Repair the short to voltage on the circuit.
  - Go to next step: If less than 1 V
5. Ignition/Vehicle - Off
6. Test for infinite resistance between the test points:
  - Control circuit terminal 1 @ Component harness & Ground
  - Control circuit terminal 2 @ Component harness & Ground
  - If less than infinite resistance - Repair the short to ground on the circuit.
  - Go to next step: If infinite resistance
7. Test for less than 2 ohms between the test points:
  - Control circuit terminal 1 @ Component harness & Terminal G @ S79P Window Switch - Passenger
  - Control circuit terminal 2 @ Component harness & Terminal F @ S79P Window Switch - Passenger
    - If 2 ohms or greater - Repair the open/high resistance in the circuit.
    - If less than 2 ohms - Replace the component: S79P Window Switch - Passenger
- Go to next step: If the specified state
Test or replace the component: M74P Window Motor - Passenger

Test 3

Ignition/Vehicle & All vehicle systems - Off
Disconnect the electrical connector: S79P Window Switch - Passenger
Ignition - On / Vehicle - In Service Mode
Verify a test lamp turns On between the test points:Ignition circuit terminal A & Ground
- If the test lamp does not turn On and the circuit fuse is OK
1. Ignition/Vehicle - Off & Remove - Test lamp
2. Test for less than 2 ohms between the test points:Ignition circuit terminal A & Output terminal @ CB2PA Fuse
  - If 2 ohms or greater - Repair the open/high resistance in the circuit.
  - If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
- Go to next step: If the test lamp turns On
Test or replace the component: S79P Window Switch - Passenger

RENDER: 1.0x

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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.