Volt

Power Windows Malfunction

The window motors are supplied with B+ voltage which is used to power the motor and also used as a reference voltage within the logic circuit. When the driver or passenger window switch is pressed, a switch is closed causing the reference voltage in the appropriate circuit in the window motor to drop, the window motor responds by moving the window in the direction commanded.

The loss of the express up and express down functions for the driver window may have occurred for the following reasons:

The driver window motor will need to be normalised in order to restore the express functions, refer to Window Motor Programming - Express Function for the proper procedure.

Schematic Reference

Moveable Window Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Power Windows Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Vehicle in Service Mode, command the M74D window motor-driver UP, DOWN, express UP and express DOWN with a scan tool. The M74D window motor--driver should perform the UP, DOWN, express UP and express DOWN commands.

⇒	If the M74D window motor--driver does perform as specified, refer to Driver Window Motor Malfunction.

2. Command the M74D window motor--driver UP, DOWN, express UP and express DOWN by using the S79D window switch-driver. The M74D window motor--driver should perform the UP, DOWN, express UP and express DOWN commands.

⇒	If the M74D window motor-driver does perform as specified, refer to Driver Window Switch Malfunction.

3. Observe the scan tool Left Rear Main Control Down Switch, Left Rear Main Control Express Switch, Left Rear Main Control Up Switch, Right Rear Main Control Down Switch, Right Rear Main Control Express Switch, Right Rear Main Control Up Switch, Front Passenger Main Control Down Switch, Front Passenger Main Control Express Switch, and the Front Passenger Main Control Up Switch parameters while using the appropriate switches on the S79D window switch-driver. Each value should change from Inactive to Active as the switch is used.

⇒	If the values do not change or if the value is No Communication, refer to Driver Window Switch Malfunction.

4. Command the passenger and rear windows UP and DOWN by using their respective S79 window switch, each window should perform the UP and DOWN functions from each switch.

⇒	If a window does not perform as specified, refer to Passenger/Rear Window Malfunction.

5. Observe the scan tool Window Lockout Switch parameter while pressing the window lockout switch on the S79D window switch-driver, the value should change from Inactive to Active each time the switch is pressed.

⇒	If the value does not change, replace the S79D window switch-driver.

Driver Window Motor Malfunction

1. Vehicle OFF, disconnect the harness connector at the M74D window motor-driver.
2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Vehicle in Service Mode, verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Test for 5-10 V between the serial data circuit terminal 4 and ground.

⇒	If greater than the specified range, test the serial data circuit for a short to voltage.

⇒	If less than the specified range, test the serial data circuit for a short to ground or an open/high resistance.

5. If all circuits test normal, test or replace the M74D window motor-driver.

Driver Power Window Switch Malfunction

1. Vehicle OFF, disconnect the harness connector at the S79D window switch-driver.
2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for and open/high resistance.

3. Vehicle in Service Mode, verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Verify that the scan tool Driver Window Main Control Down Switch parameter is Inactive.

⇒	If not the specified value, test the control circuit terminal 3 for a short to ground. If the circuit tests normal, test or replace the M74D window motor-driver.

5. Connect a 5 A fused jumper wire between the control circuit terminal 3 and ground, verify that the scan tool Driver Window Main Control Down Switch parameter is Active.

⇒	If not the specified value, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the M74D window motor-driver.

6. Verify that the scan tool Driver Window Main Control Up Switch parameter is Inactive.

⇒	If not the specified value, test the control circuit terminal 6 for a short to ground. If the circuit tests normal, test or replace the M74D window motor-driver.

7. Connect a 5 A fused jumper wire between the control circuit terminal 6 and ground, verify that the scan tool Driver Window Main Control Up Switch parameter is Active.

⇒	If not the specified value, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the M74D window motor-driver.

8. Verify that the scan tool Driver Window Main Control Express Switch parameter is Inactive.

⇒	If not the specified value, test the control circuit terminal 2 for a short to ground. If the circuit tests normal, test or replace the M74D window motor-driver.

9. Connect a 5 A fused jumper wire between the control circuit terminal 2 and ground, verify that the scan tool Driver Window Main Control Express Switch parameter is Active.

⇒	If not the specified value, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the M74D window motor-driver.

10. If all circuits test normal, test or replace the S79D window switch-driver.

Passenger/Rear Window Malfunction

1. Vehicle OFF, disconnect the harness connector at the appropriate S79 window switch.
2. Test for less than 10 Ω between the ground circuit terminal listed below and ground.

•	S79P window switch-passenger ground circuit terminal 1

•	S79LR window switch-left rear ground circuit terminal 3

•	S79LR window switch-left rear ground circuit terminal 5

•	S79RR window switch-right rear ground circuit terminal 5

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Vehicle in Service Mode, verify that a test lamp illuminates between the B+ circuit terminal listed below and ground.

•	S79P window switch-passenger B+ circuit terminal 4

•	S79LR window switch-left rear B+ circuit terminal 8

•	S79RR window switch-right rear B+ circuit terminal 8

⇒	If the test lamp does not illuminate, test the ground circuit for a short to ground or an open/high resistance.

4. Test for 5-10 V between the serial data circuit terminal listed below and ground.

•	S79P window switch-passenger serial data circuit terminal 5

•	S79LR window switch-left rear serial data circuit terminal 1

•	S79RR window switch-right rear serial data circuit terminal 1

⇒	If greater than the specified range, test the serial data circuit for a short to voltage.

⇒	If less than the specified range, test the serial data circuit for a short to ground or an open/high resistance.

5. Vehicle OFF, connect the harness connector at the S79 window switch and disconnect the harness connector at the appropriate M74 window motor.
6. Test for less than 15 Ω between the control circuit terminal A and ground.

⇒	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 appropriate S79 window switch.

7. Test for less than 15 Ω between the control circuit terminal B and ground.

⇒	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 appropriate S79 window switch.

8. Connect a test lamp between the control circuit terminal A and control circuit terminal B.
9. Vehicle in Service Mode, command the M74 window motor UP and DOWN by using the S79 window switch. The test lamp should briefly illuminate during the UP and DOWN commands.

⇒	If the test lamp does not illuminate during the UP or DOWN command, test either control circuit for a short to ground. If the circuits tests normal, replace the S79 window switch.

10. If all circuits test normal, test or replace the M74 window motor.

Passenger/Rear Window Motor

1. Vehicle OFF, disconnect the harness connector at the appropriate M74 window motor.
2. Install a 25 A fused jumper wire between one of the control terminals and 12 V. Momentarily install a jumper wire between the other control terminal and ground. Reverse the jumper wires at least two times, the M74 window motor should perform the UP and DOWN functions.

⇒	If it does not perform as specified, replace the M74 window motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.