LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 2024 >> LYRIQ Tech, AWD >> Repair and Diagnosis >> Hybrid/Electric Powertrain >> Electric Converters and Controllers >> Hybrid/EV Controls >> Diagnostic Information and Procedures >> DC Power Conversion Test >> Circuit/System Testing
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Circuit/System Testing

NOTE:

If a carbon pile tester and ammeter is available, refer to With Carbon Pile Tester section. Otherwise, refer to Without Carbon Pile Tester section.

With Carbon Pile Tester

    NOTE:

    Requires carbon pile tester rated to a minimum 200 amps along with either a built-in ammeter or a clamp-on ammeter.

  1. Vehicle Power Mode state - OFF 
  2. {If equipped} {With X0E} Visually inspect and wiggle the 12V B+ battery cable at the to the T18 Battery Charger for being loose.
    • If a condition exists - Repair or replace as necessary 

      Remove necessary components to gain access to fastener and the battery cable.

    • Go to next step: If no condition exists 

      Go to next step: Go to Step 4

  3. {If equipped} {With X0D} Verify a test lamp illuminates between the 12V B+ circuit ring terminal X6 at the T18 Battery Charger and ground.
    • If the test lamp does not illuminate 
  4. Inspect the following fuses for being open:
    • Inspect the F1UB 350A fuse at the X5AP Engine Wiring Harness Junction Block - Terminal Block for being open.
    • Inspect the F4BA 350A fuse at the X50D Battery Distribution Engine Compartment Fuse Block for being open.
      • If the fuse is open
    1. Remove the test lamp and disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection
    2. Disconnect the T18 Battery Charger 12V B+ cable.
    3. Test for infinite resistance between the 12V B+ circuit and ground.
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance

        Go to next step: Replace - Fuse

    4. Operate the vehicle within the conditions of the customer's concern.
      • The fuse opens
      • Recheck for short to ground on the 12V B+ circuit
      • Go to next step: The fuse does not open
    5. All OK.
      • If the fuse is not open
    6. Remove the test lamp and disconnect the 12V B+ cable at the T18 Battery Charger.
    7. Test for less than 2 Ω in the 12V B+ circuit end to end.
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • Go to next step: If the test lamp illuminates 
    5. NOTE:

    The vehicle must be capable of providing high voltage in order for the 14V power module to provide 12V current.

  5. Verify that no K16 Battery Energy Control Module or B110 Battery Monitor Module DTCs are set that would cause a charging system concern.
    • Go to next step: If no DTC is set 
  6. Vehicle Power Mode state - OFF 
  7. Test for 12.4 V or greater at room temperature across the C1 Battery terminals 12 minutes after turning the vehicle OFF.
    • Go to next step: If within the specified range 
    8. NOTE:

    If using a clamp-on ammeter, place it around the C1 Battery negative cable.

  8. Connect a carbon pile tester to the C1 Battery.
    9. NOTE:

    Power steering is active when propulsion is active

  9. Vehicle Power Mode state - Propulsion Active  and turn all accessories off.
  10. Observe the voltage reading on the tester. The voltage should read between 12.6 - 15.5 V.
  11. Adjust the carbon pile tester so that the ammeter is reading 200 amps.
  12. Verify the voltage reading remains between 12.6 - 15.5 V.
    • If not in the specified range 
    1. Verify DC Power set point in K16 Battery Energy Control Module data list for the K1 14-volt power module is above battery voltage.
      • If 14 volt set point is at or below battery voltage
      2. NOTE:

      Power steering is active when propulsion is inactive

    2. Vehicle Power Mode State: Service/Run 
    3. Turn off all accessories.
    4. Disconnect the X1 connector at the T18 battery charger.
    5. Test for 3.0 - 5.5V between the control circuit terminal and ground:
      • {If equipped} RPO X0D X1 - 02 to ground
      • {If equipped} RPO X0C X1 - 23 to ground
      • {If equipped} RPO X0B/X0E X1 - 43 to ground
      • If less than 3.0 V
      1. Vehicle Power Mode State: OFF 
      2. Wait 12 minutes and then disconnect the harness connectors at the K16 battery energy control module.
      3. Test for less than 2Ω in the control circuit end to end.
        • If greater than 2 ohms

          Repair the open/high resistance in the circuit.

        • Go to next step: If less than 2 ohms
      4. T18 Battery Charger - Replace
      • Go to next step: If within 3.0 - 5.5 V
    6. T18 Battery Charger - Replace
      • Go to next step: If 14 volt set point is above current battery voltage replace the 14 volt power module.
    • Go to next step: If within the specified range 
  13. All OK.

Without Carbon Pile Tester

  1. Vehicle Power Mode State: Service/Run 
  2. {If equipped} {With X0E} Visually inspect and wiggle the 12V B+ battery cable at the to the T18 Battery Charger for being loose.
    • If a condition exists - Repair or replace as necessary 

      Remove necessary components to gain access to the fastener and the battery cable.

    • Go to next step: If no condition exists 

      Go to next step: Go to Step 4

  3. {If equipped} {With X0D} Verify a test lamp illuminates between the 12V B+ circuit ring terminal X6 at the T18 Battery Charger and ground.
    • If the test lamp does not illuminate 
  4. Inspect the following fuses for being open:
    • Inspect the F1UB 350A fuse at the X5AP Engine Wiring Harness Junction Block - Terminal Block for being open.
    • Inspect the F4BA 350A fuse at the X50D Battery Distribution Engine Compartment Fuse Block for being open.
      • If the fuse is open
    1. Remove the test lamp and disconnect the battery negative cable. Refer to Battery Negative Cable Disconnection and Connection
    2. Disconnect the T18 Battery Charger 12V B+ cable.
    3. Test for infinite resistance between the 12V B+ circuit and ground.
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance

        Go to next step: Replace the open fuse.

    4. Operate the vehicle within the conditions of the customer's concern.
      • The fuse opens
      • Recheck for short to ground on the 12V B+ circuit
      • Go to next step: The fuse does not open
    5. All OK.
      • If the fuse is not open
    6. Remove the test lamp and disconnect the 12V B+ cable at the T18 Battery Charger.
    7. Test for less than 2 Ω in the 12V B+ circuit end to end.
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.
    • Go to next step: If the test lamp illuminates 
    5. NOTE:

    The vehicle must be capable of providing high voltage in order for the 14V power module to provide 12V current.

  5. Verify that no K16 Battery Energy Control Module or B110 Battery Monitor Module DTCs are set that would cause a charging system concern.
    • Go to next step: If no DTC is set 
  6. Vehicle Power Mode State: Off  and wait 12 minutes.
  7. Test for 12V or greater at room temperature across the C1 Battery terminals.
    • Go to next step: If within the specified range 
  8. Vehicle Power Mode State: Service/Run 
  9. Verify the scan tool Ignition and Start Signal parameter continually increases when controlling the 14V Power Module Setpoint from 10 - 80% with a scan tool. It may take up to 10 s for the battery voltage to stabilize between each setpoint change.
    • If the battery voltage does not continually increase 
    1. Vehicle Power Mode State: Service/Run  and turn all accessories off.
    2. Disconnect the X1 connector at the T18 Battery Charger.
    3. Test for 3.0 - 5.5 V between the control circuit terminal and ground:
      • {If equipped} RPO X0D X1 - 02 to ground
      • {If equipped} RPO X0C X1 - 23 to ground
      • {If equipped} RPO X0B/X0E X1 - 43 to ground
      • If less than 3.0 V 
      1. Vehicle Power Mode State: OFF 
      2. Disconnect the harness connectors at the K16 battery energy control module.
      3. Test for less than 2 Ω in the control circuit end to end.
        • If greater than 2 ohms

          Repair the open/high resistance in the circuit.

        • Go to next step: If less than 2 ohms
      4. T18 Battery Charger - Replace
      • Go to next step: If within 3.0 - 5.5 V
    4. T18 Battery Charger - Replace
    • Go to next step: If the battery voltage continually increases 
  10. All OK.
scientia non olet · About LEMON Manuals