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