Circuit/System Testing

2013 Buick Regal Turbo Premium, Standard TransSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2012 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition ON, with a scan tool verify the ECM Ignition 1 Signal parameter is greater than 10 V.
    • If less than the specified range, test the ECM ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  2. Ignition OFF, disconnect the KR27 starter relay.
  3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5.0 Ξ© between the relay ground circuit terminal 86 and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse or starter fuse is open, test the control circuit terminal 87 for a short to ground.
  5. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.
    • If the test lamp illuminates, test the control circuit terminal 87 for a short to voltage.
  6. Ensure the parking brake is applied and the T12 transmission is in PARK. Momentarily install a 30 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the M64 starter motor is activated.
    • If the M64 starter motor does not activate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the M64 starter motor.
  7. Connect a test lamp between the control circuit terminal 85 and the ground circuit terminal 86.
  8. Transmission in park/neutral, command the starter relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
    • If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  9. If all circuits test normal, test or replace the KR27 starter relay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.