LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2018 >> XT5 Base, FWD >> Repair and Diagnosis >> Body & Frame >> Windows >> Fixed And MOVEABLE Window System >> Diagnostic Information and Procedures >> Power Windows Malfunction >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

Test 1

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the appropriate electrical connector:
    • M35D Window Motor Module - Driver
    • M35P Window Motor Module - Passenger
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 1 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: M74 Window Motor Ground circuit terminal 1 @ Component harness & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: B+ circuit terminal 2 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points: M74 Window Motor B+ circuit terminal 2 @ Output terminal & Fuse
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal 2 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M74 Window Motor
    • Go to next step: If the test lamp turns On 
  6. Test or replace the component: M74 Window Motor

Test 2

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S79D Window Switch - Driver
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 24 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 24 @ Component harness & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: B+ circuit terminal 23 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal 23 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: S79D Window Switch - Driver
    • Go to next step: If the test lamp turns On 
  6. Verify the scan tool parameter: Driver Window Main Control Down Switch = Inactive
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: M35D Window Motor Module - Driver
    3. Test for infinite resistance between the test points: Signal circuit terminal 1 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M35D Window Motor Module - Driver
    • Go to next step: If the specified state 
  7. Momentarily connect a 3 A fused jumper wire between the test points: Signal circuit terminal 1 & Ground circuit terminal 24

    Verify the scan tool parameter: Driver Window Main Control Down Switch = Active

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: M35D Window Motor Module - Driver
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 1 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 1 @ Component harness & Signal circuit terminal 7 @ M35D Window Motor Module - Driver
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: M35D Window Motor Module - Driver
    • Go to next step: If the specified state 
  8. Verify the scan tool parameter: Driver Window Main Control Up Switch = Inactive
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: M35D Window Motor Module - Driver
    3. Test for infinite resistance between the test points: Signal circuit terminal 11 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M35D Window Motor Module - Driver
    • Go to next step: If the specified state 
  9. Momentarily connect a 3 A fused jumper wire between the test points: Signal circuit terminal 11 & Ground circuit terminal 24

    Verify the scan tool parameter: Driver Window Main Control Up Switch = Active

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: M35D Window Motor Module - Driver
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 11 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 11 @ Component harness & Signal circuit terminal 3 @ M35D Window Motor Module - Driver
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: M35D Window Motor Module - Driver
    • Go to next step: If the specified state 
  10. Test for greater than 10 V between the test points: Signal circuit terminal 5 @ Component harness & Ground
    • If 10 V or less 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: M35D Window Motor Module - Driver
    3. Test for infinite resistance between the test points: Signal circuit terminal 5 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If less than infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 5 @ Component harness & Signal circuit terminal 5 @ M35D Window Motor Module - Driver
    • If 2 ohms or greater - Repair the open/high resistance in the circuit.
    • If less than 2 ohms - Replace the component: M35D Window Motor Module - Driver
    • Go to next step: If greater than 10 V 
  11. Test or replace the component: S79D Window Switch - Driver

Test 3

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: S79P Window Switch - Passenger
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 24 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 24 @ Component harness & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify the scan tool parameter: Passenger Window Switch at Door = Inactive
    • If not the specified state 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: M35P Window Motor Module - Passenger
    3. Test for infinite resistance between the test points:
      • Signal circuit terminal 1 @ Component harness & Ground
      • Signal circuit terminal 11 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M35P Window Motor Module - Passenger
    • Go to next step: If the specified state 
  6. Momentarily connect a 3 A fused jumper wire between the test points: Signal circuit terminal 11 @ Component harness & Ground
  7. Verify the scan tool parameter: Passenger Window Switch at Door = Up
    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: M35P Window Motor Module - Passenger
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 11 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 11 @ Component harness & Signal circuit terminal 3 @ M35P Window Motor Module - Passenger
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: M35P Window Motor Module - Passenger
    • Go to next step: If the specified state 
  8. Momentarily connect a 3 A fused jumper wire between the test points: Signal circuit terminal 1 @ Component harness & Ground
  9. Verify the scan tool parameter: Passenger Window Switch at Door = Down
    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Jumper wire(s)
    2. Disconnect the electrical connector: M35P Window Motor Module - Passenger
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal 1 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for less than 2 ohms between the test points: Signal circuit terminal 1 @ Component harness & Signal circuit terminal 7 @ M35P Window Motor Module - Passenger
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: M35P Window Motor Module - Passenger
    • Go to next step: If the specified state 
  10. Test for greater than 10 V between the test points: Signal circuit terminal 13 @ Component harness & Ground
    • If 10 V or less 
    1. Ignition/Vehicle - Off
    2. Disconnect the electrical connector: M35P Window Motor Module - Passenger
    3. Test for infinite resistance between the test points: Signal circuit terminal 13 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If less than infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal 13 @ Component harness & Signal circuit terminal 5 @ M35P Window Motor Module - Passenger
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: M35P Window Motor Module - Passenger
      • Go to next step: If greater than 10 V 
  11. Test or replace the component: S79P Window Switch - Passenger

Test 4

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the appropriate electrical connector:
    • S79RR Window Switch - Right Rear
    • S79LR Window Switch - Left Rear
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 7 & Ground
    • If 10 ohms or greater 
    1. Ground Connection - Disconnect
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 7 @ Component harness & Ground Connection
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  4. Ignition - On/Vehicle - In Service Mode
  5. Verify a test lamp turns On between the test points: B+ circuit terminal 8 & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal 8 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: S79RR Window Switch - Right Rear/S79LR Window Switch - Left Rear
    • Go to next step: If the test lamp turns On 
  6. Ignition/Vehicle - Off
  7. Connect the electrical connector: S79RR Window Switch - Right Rear/S79LR Window Switch - Left Rear
  8. Disconnect the electrical connector: M74 Window Motor
  9. Connect a test lamp between the test points: Control circuit terminal 1 & Control circuit terminal 2
  10. Ignition - On/Vehicle - In Service Mode
  11. Perform the scan tool control function: Window Motor

    Verify the test lamp state:

    Window Motor - Stop = Test lamp Off

    Window Motor - Up = Test lamp On

    Window Motor - Down = Test lamp On

    • If not the specified state 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: S79RR Window Switch - Right Rear/S79LR Window Switch - Left Rear
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points:
      • Control circuit terminal 1 @ Component harness & Ground
      • Control circuit terminal 2 @ Component harness & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • Go to next step: If less than 1 V
    5. Ignition/Vehicle - Off
    6. Test for infinite resistance between the test points:
      • Control circuit terminal 1 @ Component harness & Ground
      • Control circuit terminal 2 @ Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    7. Test for less than 2 ohms between the test points:
      • Control circuit terminal 1 @ Component harness & Control circuit terminal 9 @ S79LR Window Switch - Left Rear
      • Control circuit terminal 2 @ Component harness & Control circuit terminal 10 @ S79LR Window Switch - Left Rear
      • Control circuit terminal 1 @ Component harness & Control circuit terminal 9 @ S79RR Window Switch - Right Rear
      • Control circuit terminal 2 @ Component harness & Control circuit terminal 10 @ S79RR Window Switch - Right Rear
        • If 2 ohms or greater - Repair the open/high resistance in the circuit.
        • If less than 2 ohms - Replace the component: S79RR Window Switch - Right Rear/S79LR Window Switch - Left Rear
    • Go to next step: If the specified state 
  12. Test or replace the component: M74 Window Motor
scientia non olet · About LEMON Manuals