Circuit/System Testing

Window Motor Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate M74 Window Motor. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.
   • If 10 Ω or greater 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
   • If less than 10 Ω 
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 2 and ground.
   • If the test lamp does not illuminate and the circuit fuse is good 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
   • If the test lamp does not illuminate and the circuit fuse is open 
   1. Ignition OFF.
   2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the M74 window motor.
   • If the test lamp illuminates 
5. Test or replace the M74 Window Motor.

Driver Window Switch Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S79D Window Switch-Driver. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.
   • If 10 Ω or greater 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
   • If less than 10 Ω 
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 4 and ground.
   • If the test lamp does not illuminate and the circuit fuse is good 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.
   • If the test lamp does not illuminate and the circuit fuse is open 
   1. Ignition OFF.
   2. Test for infinite resistance between the B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the S79D Window Switch-Driver.
   • If the test lamp illuminates 
5. Verify the scan tool Driver Window Main Control Down Switch parameter is Inactive.
   • If not Inactive 
   1. Ignition OFF, disconnect the harness connector at the M74D Window Motor-Driver.
   2. Test for infinite resistance between the S79D Window Switch-Driver signal circuit terminal 3 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the M74D Window Motor-Driver.
   • If Inactive 
6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 1.
7. Verify the scan tool Driver Window Main Control Down Switch parameter is Active
   • If not Active 
   1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the M74D Window Motor-Driver, ignition ON.
   2. Test for less than 1 V between the S79D Window Switch-Driver signal circuit terminal 3 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
   3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the M74D Window Motor-Driver.
   • If Active 
8. Verify the scan tool Driver Window Main Control Up Switch parameter is Inactive.
   • If not Inactive 
   1. Ignition OFF, disconnect the harness connector at the M74D Window Motor-Driver.
   2. Test for infinite resistance between the S79D Window Switch-Driver signal circuit terminal 6 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the M74D Window Motor-Driver.
   • If Inactive 
9. Install a 3 A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 1.
10. Verify the scan tool Driver Window Main Control Up Switch parameter is Active
    • If not Active 
    1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the M74D Window Motor-Driver, ignition ON.
    2. Test for less than 1 V between the S79D Window Switch-Driver signal circuit 6 and ground.
       • If 1 V or greater, repair the short to voltage on the circuit.
       • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
       • If 2 Ω or greater, repair the open/high resistance in the circuit.
       • If less than 2 Ω, replace the M74D Window Motor-Driver.
    • If Active 
11. Verify the scan tool Driver Window Main Control Express Switch parameter is Inactive.
    • If not Inactive 
    1. Ignition OFF, disconnect the harness connector at the M74D Window Motor-Driver.
    2. Test for infinite resistance between the S79D Window Switch-Driver signal circuit terminal 2 and ground.
       • If less than infinite resistance, repair the short to ground on the circuit.
       • If infinite resistance, replace the M74D Window Motor-Driver.
    • If Inactive 
12. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1.
13. Verify the scan tool Driver Window Main Control Express Switch parameter is Active
    • If not Active 
    1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the M74D Window Motor-Driver, ignition ON.
    2. Test for less than 1 V between the S79D Window Switch-Driver signal circuit 2 and ground.
       • If 1 V or greater, repair the short to voltage on the circuit.
       • If less than 1 V
    3. Test for less than 2 Ω in the signal circuit end to end.
       • If 2 Ω or greater, repair the open/high resistance in the circuit.
       • If less than 2 Ω, replace the M74D Window Motor-Driver.
    • If Active 
14. Test or replace the S79D Window Switch-Driver.

Passenger/Rear Window Switch Malfunction

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate passenger or rear S79 Window Switch. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.
   • If 10 Ω or greater 
   1. Ignition OFF.
   2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
   • If less than 10 Ω 
3. Ignition ON.
4. Verify the appropriate scan tool Window Switch at Door parameter is Inactive.
   • If not Inactive 
   1. Ignition OFF, disconnect the harness connector at the M74 Window Motor.
   2. Test for infinite resistance between the signal circuit terminal listed below and ground:
      • S79P Window Switch-Passenger - signal circuit terminal 7
      • S79P Window Switch-Passenger - signal circuit terminal 8
      • S79LR Window Switch-Left Rear - signal circuit terminal 6
      • S79LR Window Switch-Left Rear - signal circuit terminal 7
      • S79RR Window Switch-Right Rear - signal circuit terminal 6
      • S79RR Window Switch-Right Rear - signal circuit terminal 7
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the M74 Window Motor.
   • If Inactive 
5. Install a 3 A fused jumper wire between the circuit terminal listed below and ground:
   • S79P Window Switch-Passenger - signal circuit terminal 8
   • S79LR Window Switch-Left Rear - signal circuit terminal 6
   • S79RR Window Switch-Right Rear - signal circuit terminal 6
6. Verify the scan tool Window Switch at Door parameter is Up
   • If not Up 
   1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the M74 Window Motor, ignition ON.
   2. Test for less than 1 V between the circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
   3. Ignition OFF, test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the M74 Window Motor.
   • If Up 
7. Install a 3 A fused jumper wire between the signal circuit terminal 7 and ground.
8. Verify the scan tool Window Switch at Door parameter is Down
   • If not Down 
   1. Ignition OFF, remove the 3 A fused jumper wire, disconnect the harness connector at the M74 Window Motor, ignition ON.
   2. Test for less than 1 V between the S79 Window Switch signal circuit terminal 7 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
   3. Ignition OFF, test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the M74 Window Motor.
   • If Down 
9. Test for greater than 10 V between the signal circuit terminal listed below and ground:
   • S79P Window Switch-Passenger - signal circuit terminal 6
   • S79LR Window Switch-Left Rear - signal circuit terminal 8
   • S79RR Window Switch-Right Rear - signal circuit terminal 8
   • If less than 10 V 
   1. Ignition OFF, disconnect the harness connector at the M74 Window Motor.
   2. Test for infinite resistance between the signal circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
   3. Test for less than 2 Ω in the signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance on the circuit.
      • If less than 2 Ω, replace the M74 Window Motor.
   • If greater than 10 V 
10. Test or replace the passenger or rear S79 Window Switch.