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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 228 (Vehicle Access System - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Power Door Locks Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.

Test 1

  1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the S13D Door Lock Switch-Driver.
  2. Verify a test lamp illuminates between ground circuit terminal 4 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 2150 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition - On/Vehicle - In Service Mode
  4. Verify the scan tool Left Front Door Interior Lock Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 2771 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • Go to next step: If Inactive 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground.
  6. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 2771 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 2771 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • Go to next step: If Active 
  7. Verify the scan tool Left Front Door Interior Unlock Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 2772 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • Go to next step: If Inactive 
  8. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground.
  9. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 2772 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 2772 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the S79D Front Side Door Window Control Switch-Driver.
    • Go to next step: If Active 
  10. Replace the S13D Door Lock Switch-Driver.

Test 2

  1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the S13P Door Lock Switch-Passenger.
  2. Verify a test lamp illuminates between ground circuit terminal 4 and B+.
    • If the test lamp does not illuminate 
    1. Repair the open/high resistance on circuit 2250 or the ground connection.
    • Go to next step: If the test lamp illuminates 
  3. Ignition - On/Vehicle - In Service Mode
  4. Verify the scan tool Right Front Door Interior Lock Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 2773 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • Go to next step: If Inactive 
  5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground.
  6. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 2773 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 2773 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • Go to next step: If Active 
  7. Verify the scan tool Right Front Door Interior Unlock Status parameter is Inactive
    • If not Inactive 
    1. Test the circuit 2774 for a short to ground
      • If a short to ground is found, repair the fault on the circuit.
      • Go to next step: If a short to ground is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • Go to next step: If Inactive 
  8. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground.
  9. Verify the scan tool parameter is now Active.
    • If not Active and the 3 A fuse is OK 
    1. Test the circuit 2774 for an open/high resistance.
      • If an open/high resistance is found, repair the fault on the circuit.
      • Go to next step: If an open/high resistance is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • If not Active and the 3 A fuse is open 
    1. Test the circuit 2774 for a short to voltage.
      • If a short to voltage is found, repair the fault on the circuit.
      • Go to next step: If a short to voltage is not found.
    2. Replace the S79P Front Side Door Window Switch-Passenger.
    • Go to next step: If Active 
  10. Replace the S13P Door Lock Switch-Passenger.

Test 3

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: A23D Front Side Door Latch-Driver
  3. Connect a test lamp between the test points: Control circuit terminal 7 & ground
  4. Ignition - On/Vehicle - In Service Mode
  5. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Lock Switch - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2681 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2681 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 1 V between the circuit 2681 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  6. Connect a test lamp between the test points: Control circuit terminal 8 & ground
  7. Ignition - On/Vehicle - In Service Mode
  8. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Unlock - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2679 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2679 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module.
    2. Test for less than 1 V between the circuit 2679 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  9. Test or replace the component: A23D Front Side Door Latch-Driver

Test 4

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: A23P Front Side Door Latch-Passenger
  3. Connect a test lamp between the test points: Control circuit terminal 8 & ground
  4. Ignition - On/Vehicle - In Service Mode
  5. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Lock Switch - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2680 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2680 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 2680 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  6. Connect a test lamp between the test points: Control circuit terminal 9 & ground
  7. Ignition - On/Vehicle - In Service Mode
  8. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Unlock - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2682 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2682 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 2682 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  9. Test or replace the component: A23P Front Side Door Latch-Passenger

Test 5

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: A23LR Rear Side Door Latch-Left
  3. Connect a test lamp between the test points: Control circuit terminal 7 & ground
  4. Ignition - On/Vehicle - In Service Mode
  5. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Lock Switch - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 1091 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 1091 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 1091 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  6. Connect a test lamp between the test points: Control circuit terminal 8 & ground
  7. Ignition - On/Vehicle - In Service Mode
  8. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Unlock - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2679 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2679 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 2679 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  9. Test or replace the component: A23LR Rear Side Door Latch-Left

Test 6

  1. Ignition/Vehicle - Off
  2. Disconnect the electrical connector: A23RR Rear Side Door Latch-Right
  3. Connect a test lamp between the test points: Control circuit terminal 8 & ground
  4. Ignition - On/Vehicle - In Service Mode
  5. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Lock Switch - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 2680 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 2680 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 2680 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  6. Connect a test lamp between the test points: Control circuit terminal 9 & ground
  7. Ignition - On/Vehicle - In Service Mode
  8. Operate the component: S13D Door Lock Switch - Driver

    Verify the test lamp state:

    Not used = Test lamp Off

    Unlock - Pressed = Test lamp flashes ON and OFF

    • If the test lamp is always OFF 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module
    2. Test for infinite resistance between the circuit 1094 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the circuit 1094 end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K9 Body Control Module
    • If the test lamp is always ON 
    1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K9 Body Control Module, ignition ON.
    2. Test for less than 1 V between the circuit 1094 and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K9 Body Control Module
    • Go to next step: If the test lamp turns ON and OFF 
  9. Test or replace the component: A23RR Rear Side Door Latch-Right
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