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Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2020 Buick Regal TourX, 2020 Buick Regal, 2019 Buick Regal TourX, 2019 Buick Regal, and 2018 Buick Regal TourX. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • Use the wiring schematics to identify the items/configurations listed below:
    • Control modules the vehicle is equipped with
    • The control module's B+, ignition, and ground circuits
    • The control module's circuit terminals and connectors
  • Some control module ground circuits may require up to 20 min after the ignition is turned Off before achieving a resistance reading of less than 5 ohms. In most cases the readings will drop below 20 ohms within 1 min indicating the control modules are going to sleep.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: Appropriate control module.
  3. Test for less than 10 ohms between the test points: Each ground circuit terminal & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: Ground terminal
    2. Test for less than 2 ohms between the test points: Ground circuit terminal @ Control module harness & The other end of the circuit
      • 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. Verify a test lamp turns On between the test points: Each B+ circuit terminal & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Remove - Test Lamp
    2. Test for less than 2 ohms between the test points: B+ circuit terminal @ Control module harness & 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. Remove - Test Lamp
    2. Test for infinite resistance between the test points: B+ circuit terminal @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: Control Module
    • Go to next step: If the test lamp turns On 
  5. Ignition - On/Vehicle - In Service Mode
  6. Verify a test lamp turns On between the test points: Each ignition circuit terminal & 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: Ignition circuit terminal @ Control module harness & 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: Ignition circuit terminal @ Control module harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: Control Module
    • Go to next step: If the test lamp turns On 
  7. Replace the component: Control Module
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