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Power Windows Malfunction




Power Windows Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

When a window switch is pressed on the driver window switch, a serial data message is sent to the body control module (BCM). The BCM examines the request and checks for messages from other power window motors prohibiting the window movement. If no prohibitive messages have been received, the BCM will send a serial data message to the passenger window motor or to the appropriate rear window switch which will perform the command as requested.

Each power window motor is controlled by their respective window switches. When a power window switch is activated to a desired position, power window switch will send a signal to its respective door window motor to move the window to the desired position.

Diagnostic Aids

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

* The battery was disconnected

* The battery was replaced

* A door wiring harness was disconnected

* A window motor was disconnected or replaced

The window motors will need to be normalized in order to restore the express functions, refer to Window Motor Programming - Express Function Testing and Inspection for the proper procedure.

Reference Information

Schematic Reference

Moveable Window Schematics Electrical Diagrams

Connector End View Reference

Component Connector End Views Connector End Views By Name

Description and Operation

Power Windows Description and Operation Power Windows

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Programming and Relearning for scan tool information

Circuit/System Verification

1. Ignition ON, command the driver, passenger, left rear and right rear window UP and DOWN with a scan tool, Each window should perform the UP and DOWN commands.

• If the driver and passenger windows do not perform as specified, refer to Both Front Windows Inoperative.

• If the driver window does not perform as specified, refer to Single Front Window Motor Inoperative.

• If the passenger window does not perform as specified, refer to Single Front Window Motor Inoperative.

• If the left rear window does not perform as specified, refer to Rear Window Inoperative.

• If the right rear window does not perform as specified, refer to Rear Window Inoperative.

2. Command the driver window UP, DOWN, Express UP and Express DOWN with the driver window switch, The driver window should perform the UP, DOWN, Express UP and Express DOWN commands.

• If the driver window does perform as specified, refer to Driver Window 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 driver window switch. The values should change from Inactive to Active for each switch used.

• If any of the values are always Inactive or always Active, refer to Driver Switches Malfunction.

4. Command the passenger window UP, DOWN, Express UP and Express DOWN with the passenger window switch, The passenger window should perform the UP, DOWN, Express UP and Express DOWN commands.

• If the passenger window does perform as specified, refer to Passenger Window Malfunction.

Circuit/System Testing

Both Front Windows Inoperative

1. Ignition OFF, disconnect the harness connector at the S79D window switch-driver.

2. Disconnect the harness connector at the M74D window motor-driver

3. Disconnect the harness connector at the M74P window motor-passenger

4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal listed below and ground.

* B+ circuit terminal 2-M74D window motor-driver

* B+ circuit terminal 2-M74P window motor-passenger

• If the test lamp does not illuminate and the B+ circuit fuse is open, test each B+ circuit for a short to ground. If the circuit tests normal, test for a shorted front M74 window motor.

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

* Serial data circuit terminal 4-M74D window motor-driver

* Serial data circuit terminal 5-S79D window switch-driver

* Serial data circuit terminal 4-M74P window motor-passenger

• If less than the specified range, test each serial data circuit for a short to ground.

6. If all circuits test normal, test for a shorted front M74 window motor or a shorted S79D window switch-driver

Single Front Window Motor Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate front M74 window motor.

2. After 10 minutes, test for less than 10 ohms between the ground circuit terminal 1 and ground.

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

3. Ignition ON, 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 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 an open/high resistance.

5. If all circuits test normal, replace the front M74 window motor.

Rear Window Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate rear S79 window switch.

2. Test for less than 5 ohms between the ground circuit terminal 5 and ground.

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

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 8 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 1 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. Ignition OFF, connect the harness connector at the rear S79 window switch.

6. Disconnect the harness connector at the appropriate rear M74 window motor.

7. Test for less than 5 ohms 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 rear S79 window switch.

8. Test for less than 5 ohms 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 rear S79 window switch.

9. Connect a test lamp between the control circuit terminal A and control circuit terminal B.

10. Ignition ON, command the rear window UP and DOWN using the S79R window switch-rear. The test lamp should briefly illuminate when commanding the UP and DOWN states.

• If the test lamp does not illuminate during either of the commands, test both control circuits for a short to ground. If the circuits test normal, replace the rear S79 window switch.

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

Driver Window Malfunction

1. Ignition OFF, disconnect the harness connector at the S79D window switch-driver.

2. After 10 minutes, test for less than 10 ohms between the ground circuit terminal 1 and ground.

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

3. Ignition ON, verify that the scan tool Driver Window Main Control Down Switch parameter is Inactive.

• If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the M74D window motor-driver.

4. Connect a 3 A fused jumper wire between the signal circuit terminal 7 and ground. Verify that the scan tool Driver Window Main Control Down Switch parameter is Active.

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

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

• If not the specified value, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, replace the M74D window motor-driver.

6. Connect a 3 A fused jumper wire between the signal circuit terminal 8 and ground. Verify that the scan tool Driver Window Main Control Up Switch parameter is Active.

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

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

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

8. Connect a 3 A fused jumper wire between the signal circuit terminal 6 and ground, verify the scan tool Driver Window Main Control Express Switch parameter is Active.

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

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

Driver Switches Malfunction

1. Ignition OFF, disconnect the harness connector at the S79D window switch-driver.

2. Ignition ON, 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.

3. Test for 5-10 V between the serial data circuit terminal 5 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 an open/high resistance.

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

Passenger Window Malfunction

1. Ignition OFF, disconnect the harness connector at the S79P window switch-passenger.

2. Test for less than 10 ohms between the ground circuit terminal 1 and ground.

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

3. Ignition ON, verify that the scan tool Passenger Window Switch at Door parameter is Inactive.

• If the value is Up, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, test or replace the M74P window motor-passenger.

• If the value is Down, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, test or replace the M74P window motor-passenger.

4. Connect a 3 A fused jumper wire between the signal circuit terminal 8 and ground, verify that the scan tool Passenger Window Switch at Door parameter is Up.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the M74P window motor-passenger.

5. Connect a 3 A fused jumper wire between the signal circuit terminal 7 and ground, verify that the scan tool Passenger Window Switch at Door parameter is Down.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the M74P window motor-passenger.

6. Test for greater than 10 V between the signal circuit terminal 6 and ground.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the 74P window motor-passenger.

7. If all circuits test normal, test or replace the S79P window switch-passenger.

Component Testing

1. Ignition OFF, disconnect the harness connector at the appropriate rear M74 window motor.

2. Install a 30 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 rear M74R window motor should perform the UP and DOWN functions.

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

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Front Side Door Window Switch Replacement Front Side Door Window Switch Replacement

* Rear Side Door Window Switch Replacement Rear Side Door Window Switch Replacement

* Front Side Door Window Regulator Motor Replacement Service and Repair

* Rear Side Door Window Regulator Motor Replacement Service and Repair

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