GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Main Power Window Switch Voltage Supply

1, 2

1, 2

--

--

Rear Window Lockout Switch Control

2

2

--

--

Rear Window Switch Control

2

2

2

--

Front Window Motor Control

1

1

1

--

Rear Window Motor Control

2

2

2

--

Main Power Window Switch Ground

--

1, 2

1, 2

--

1. Front Power Window Inoperative

2. Rear Power Window Inoperative

Circuit/System Description

The power window system will operate any time the ignition is the ACC or RUN position. The main power window switch located in the console contains individual window switches for each of the power windows. All windows may be controlled up and down from the main power window switch. The individual rear passenger power window switches will only control the up and down operation of their respective power window.

Each power window contains a reversible power window motor. The direction the window travels is dependent upon the polarity of the supply voltage. By reversing polarity of the supply voltage the window motor will move up or down. Each power window motor is internally circuit breaker protected.

Battery voltage is supplied to the main power window switch through the accessory voltage supply circuit. The main power window switch also receives a constant ground source. The power window motor control circuits are connected to ground through the normally closed up and down contacts of the main power window switch. When the main power window switch is placed in the down position, the power window motor down control circuit is switched to 12 volts which is applied to the down side of the power window motor. Since the other side of the power window motor is connected to ground through the normally closed contacts of the up switch, the window travels down. By placing the power window switch in the up position, the polarity of the power window motor is reversed and the window travels up.

The driver's window switch has an express-down feature that allows the window to be lowered completely without holding the switch. The switch is labeled AUTO. Press the bottom of the switch part way and release it and the driver's window will open a small amount. Press the switch all the way down and release it and the window will go completely down automatically.

To stop the window while it is lowering, press and release the top of the switch.

Diagnostic Aids

    • There is a circuit breaker found in the power window motor. After 30 seconds of continuous voltage being applied the circuit breaker will open.
    • The power window motor is a bi-directional motor. When voltage and ground are reversed the motor will reverse direction.

Reference Information

Schematic Reference

Moveable Window Schematics

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

  1. Ignition ON, command the appropriate door window UP and DOWN by pressing the appropriate Window switch. Observe the operation of the appropriate door windows.
  2. If all power windows are inoperative, refer to All Power Windows Inoperative.
    If the front driver door window or front passenger door window is inoperative, refer to Front Power Windows Inoperative.
    If the left rear door window or right rear door window is inoperative, refer to Rear Power Windows Inoperative.
    If both rear door windows are inoperative, refer to Rear Window Lockout Switch Malfunction.
  3. Ignition ON, command the express down function door window by pressing the Auto on the Driver Window switch past the first detent and releasing. The driver's window should roll completely down.
  4. If the driver's window fails to roll completely down, replace the Main Power Window Switch.

Circuit/System Testing

Rear Window Lockout Switch Malfunction

  1. Ignition ON, activate the lockout parameter by pressing the Rear Window Lockout Switch on the Main Power Window Switch. Command each of the rear passenger windows UP and DOWN using the appropriate rear door passenger window switches. Both rear door passenger window switches should be inoperative.
  2. If both rear passenger windows continue to function, test or replace the Main Power Window Switch.
  3. Ignition ON, deactivate the lockout parameter by pressing the Rear Window Lockout Switch on the Main Power Window Switch. Command each of the rear passenger windows UP and DOWN using the appropriate rear door passenger window switches. Both rear door passenger windows should function UP and DOWN as commanded.
  4. If both rear windows are inoperative, test or replace the Main Power Window Switch.

All Power Windows Inoperative

  1. Ignition OFF, disconnect the B+ harness connector C2 at the Main Power Window Switch.
  2. Ignition OFF, test for less than 1 ohm of resistance between the ground circuit terminal 6 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. If the POWER WNDW circuit breaker is open, test the B+ circuit for a short to ground. If the circuit test normal, test or replace the Underhood Fuse Block.
  6. If all circuits test normal, test or replace the Main Power Window Switch.

Front Power Window Inoperative

  1. Ignition OFF, disconnect the harness connector at the appropriate front Window Motor.
  2. Ignition OFF, test for less than 1 ohm of resistance between the control circuit terminal 1 and ground.
  3. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test of replace the Main Power Window Switch.
  4. Ignition OFF, test for less than 1 ohm of resistance between the control circuit terminal 2 and ground.
  5. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test of replace the Main Power Window Switch.
  6. Ignition ON, connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
  7. Command the appropriate front window UP and DOWN by pressing the appropriate front window control on the Main Power Window Switch, the test lamp should turn ON when commanding the UP and DOWN states.
  8. If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, test or replace the Main Power Window Switch.
  9. If all circuits test normal, test or replace the appropriate front Window Motor.

Rear Power Window Inoperative

  1. Ignition OFF, disconnect the appropriate rear Window Switch.
  2. Ignition OFF, test for less than 1 ohm of resistance between the control circuit terminal D and ground.
  3. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the Main Power Window Switch.
  4. Ignition OFF, test for less than 1 ohm of resistance between the control circuit H and ground.
  5. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the Main Power Window Switch.
  6. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground.
  7. If the test lamp does not illuminate and the Rear Window Lockout Switch is CLOSED, test the B+ circuit for an open/high resistance.
  8. Connect a test lamp between the control circuit terminal D and control circuit terminal H.
  9. Ignition ON, command the appropriate rear door window UP and DOWN by pressing the appropriate rear window control on the Main Power Window Switch. The test lamp should illuminate during either of the commands.
  10. If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If all circuits test normal, test or replace the Main Power Window Switch.
  11. Ignition OFF, reconnect the appropriate rear door Window Switch.
  12. Ignition OFF, disconnect the harness connector at the appropriate rear door Window Motor.
  13. Ignition OFF, test for less than 1 ohm of resistance between the control circuit terminal 2 and ground.
  14. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the test or appropriate rear door window switch.
  15. Ignition OFF, test for less than 1 ohm for resistance between the control circuit terminal 1 and ground.
  16. If greater than the specified range, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the appropriate rear door window switch.
  17. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2
  18. Ignition ON, be sure the Rear Window Lockout Switch is CLOSED, command the appropriate rear door window UP and DOWN by pressing the appropriate rear door Window Switch. The test lamp should turn ON when commanding the UP and DOWN states.
  19. If the test lamp remains OFF during either of the commands, test for a short to ground on either control circuit. If the circuits test normal, test or replace the appropriate rear door Window Switch.
  20. If all circuits test normal, test or replace the appropriate rear Window Motor.

Component Testing

Main Power Window Switch

  1. Ignition OFF, disconnect the harness connector at the Main Power Window switch.
  2. Test for infinite resistance between the signal terminals 2 and 5 and the B+ circuit terminal 2 with the LR Switch in the INACTIVE position.
  3. If less than infinite resistance, replace the Main Power Window switch.
  4. Test for less than 2 ohms of resistance between the signal terminal 2 and the B+ circuit terminal 2 with the switch in the UP position.
  5. If greater than the specified range, replace the Main Power Window switch.
  6. Test for less than 2 ohms of resistance between the signal terminal 5 and the B+ circuit terminal 2 with the switch in the DOWN position.
  7. If greater than the specified range, replace the Main Power Window switch.
  8. Test for infinite resistance between the signal terminals 3 and 3 and the B+ circuit terminal 2 with the RR Switch in the INACTIVE position.
  9. If less than infinite resistance, replace the Main Power Window switch.
  10. Test for less than 2 ohms of resistance between the signal terminal 3 and the B+ circuit terminal 2 with the switch in the UP position.
  11. If greater than the specified range, replace the Main Power Window switch.
  12. Test for less than 2 ohms of resistance between the signal terminal 3 and the B+ circuit terminal 2 with the switch in the DOWN position
  13. If greater than the specified range, replace the Main Power Window switch.
  14. Test for infinite resistance between the signal terminals 5 and 6 and the B+ circuit terminal 2 with the Front Passenger Switch in the INACTIVE position.
  15. If less than infinite resistance, replace the Main Power Window switch.
  16. Test for less than 2 ohms of resistance between the signal terminal 5 and the B+ circuit terminal 2 with the switch in the UP position.
  17. If greater than the specified range, replace the Main Power Window switch.
  18. Test for less than 2 ohms of resistance between the signal terminal 6 and the B+ circuit terminal 2 with the switch in the DOWN position.
  19. If greater than the specified range, replace the Main Power Window switch.
  20. Test for infinite resistance between the signal terminals 5 and 4 and the B+ circuit terminal 2 with the Driver Switch in the INACTIVE position.
  21. If less than infinite resistance, replace the Main Power Window switch.
  22. Test for less than 2 ohms of resistance between the signal terminal 5 and the B+ circuit terminal 2 with the switch in the UP position.
  23. If greater than the specified range, replace the Main Power Window switch.
  24. Test for less than 2 ohms of resistance between the signal terminal 4 and the B+ circuit terminal 2 with the switch in the DOWN position.
  25. If greater than the specified range, replace the Main Power Window switch.

Rear Window Switch

  1. Ignition OFF, disconnect the harness connector at the appropriate rear Window switch.
  2. Test for infinite resistance between the signal terminals F and G and the B+ circuit terminal A with the switch in the INACTIVE position.
  3. If less than infinite resistance, replace the appropriate rear window switch.
  4. Test for less than 2 ohms of resistance between the signal terminal F and the B+ circuit terminal A with the switch in the UP position.
  5. If greater than the specified range, replace the appropriate rear window switch.
  6. Test for less than 2 ohms of resistance between the signal terminal G and the B+ circuit terminal A with the switch in the DOWN position.
  7. If greater than the specified range, replace the appropriate rear window switch.

Window Motor

  1. Install a 25 amp fused jumper wire between the control terminal 1 and 12 volts. Momentarily install a jumper wire between the control terminal 2 and ground. The appropriate Window Motor should perform the UP or DOWN function.
  2. If the function does not perform as specified, replace the appropriate Window Motor.
  3. Reverse the jumper wires; the appropriate Window Motor should perform the DOWN or UP function.
  4. If the function does not perform as specified, replace the appropriate Window Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Front Side Door Window Switch Replacement
    •  Rear Side Door Window Switch Replacement
    •  Front Side Door Window Regulator Motor Replacement
    •  Rear Side Door Window Regulator Motor Replacement