LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Buick >> 2012 >> Regal Base >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Hybrid/EV Control System) >> Diagnostic Information and Procedures >> DTC P0B09 >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. Ignition OFF, disconnect the KR86 Transmission Fluid Pump Relay - Auxiliary, Ignition ON.
  2. Verify a test lamp illuminates between the ignition circuit terminal 86 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 ignition 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 ignition circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the KR86 Transmission Fluid Pump Relay - Auxiliary.
    • If the test lamp illuminates 
  3. Connect a test lamp between the ignition circuit terminal 86 and the control circuit terminal 85.
  4. Verify the test lamp turns ON and OFF when commanding the Auxiliary Transmission Pump Relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the X2 harness connector at the K59 starter generator control module, ignition ON.
    2. Test for less than 1 V between the control circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF.
    4. Test for less than 2 Ω in the control circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the K59 starter generator control module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K59 starter generator control module.
    2. Test for infinite resistance between the control circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, replace the K59 starter generator control module.
    • If the test lamp turns ON and OFF 
  5. Replace the K59 starter generator control module.
scientia non olet · About LEMON Manuals