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Home >> Cadillac >> 2019 >> CT6 V >> Repair and Diagnosis >> Electrical >> Charging Systems >> Battery, Charging System And Starting System >> Diagnostic Information and Procedures >> Starter Malfunction >> Circuit/System Testing
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Circuit/System Testing

Test 1

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Remove the component: KR27C Starter Pinion Solenoid Actuator Relay
  3. Test for less than 10 ohms between the test points: Ground circuit terminal 86 & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: Ground Connection @ The other end of the circuit
    2. Test for less than 2 ohms between the test points: Ground circuit terminal 86 & Ground terminal @ 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. Connect a test lamp between the test points: Control circuit terminal 85 & Ground circuit terminal 86
  5. Ignition - On/Vehicle - In Service Mode
  6. Perform the appropriate scan tool control function:
    • {If available} Starter Pinion Solenoid Actuator Relay - On and Off
    • {If available} Starter Relay - On and Off

      Verify the test lamp turns On and Off.

    • If the test lamp is always Off 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Test for infinite resistance between the test points: Control circuit terminal 85 @ Relay Socket & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Control circuit terminal 85 @ Relay Socket & The other end of the circuit @ Control module harness
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Control circuit terminal 85 @ Relay Socket & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp turns On and Off 
  7. Verify a test lamp turns On between the test points: B+ circuit terminal 30 & 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: B+ circuit terminal 30 @ Relay Socket & 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: B+ circuit terminal 30 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Disconnect the electrical connector: X1 @ M64 Starter Motor
    4. Test for infinite resistance between the test points: Control circuit terminal 87 @ Relay Socket & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    5. Replace the component: M64 Starter Motor
    • Go to next step: If the test lamp turns On 
  8. Momentarily connect a 40 A fused jumper wire between the test points: B+ circuit terminal 30 & Control circuit terminal 87

    Verify the component does not turn On and Off when connecting and disconnecting the jumper wire: Starter Pinion Solenoid Actuator

    • If the component turns On and Off 

      Test or replace the component: KR27C Starter Pinion Solenoid Actuator Relay

    • Go to next step: If the component does not turn On and Off 
  9. Ignition/Vehicle & All vehicle systems - Off
  10. Install the component: KR27C Starter Pinion Solenoid Actuator Relay
  11. Disconnect the electrical connector: X1 @ M64 Starter Motor
  12. Connect a test lamp between the test points: Control circuit terminal 2 & Ground
  13. Ignition - On/Vehicle - In Service Mode
  14. Perform the appropriate scan tool control function:
    • {If available} Starter Pinion Solenoid Actuator Relay - On and Off
    • {If available} Starter Relay - On and Off

      Verify the test lamp turns On and Off.

    • If the test lamp is always Off 

      Repair the open/high resistance in the circuit: Control Circuit

    • If the test lamp is always On 

      Repair the short to voltage on the circuit: Control Circuit

    • Go to next step: If the test lamp turns On and Off 
  15. Test or replace the component: M64 Starter Motor

Test 2

  1. Verify a test lamp turns On between the test points: B+ circuit terminal A @ M64 Starter Motor & 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: B+ circuit terminal A @ M64 Starter Motor & 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: B+ circuit terminal A @ M64 Starter Motor & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Replace the component: M64 Starter Motor
    • Go to next step: If the test lamp turns On 
  2. Verify a test lamp turns On between the test points: B+ terminal 85 @ KR27 Starter Relay & Ground
    • If the test lamp does not turn On 
      NOTE:

      It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

    1. Ignition/Vehicle & All vehicle systems - Off
    2. Test for infinite resistance between the test points: Terminal 85 @ KR27 Starter Relay & 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 ohms between the test points: Terminal 85 @ KR27 Starter Relay & 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.
    • Go to next step: If the test lamp turns On 
    3. NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  3. Ignition/Vehicle & All vehicle systems - Off
  4. Remove the component: KR27 Starter Relay
  5. Connect a test lamp between the test points: Control circuit terminal 86 & B+ terminal 85
  6. Ignition - On/Vehicle - In Service Mode
  7. Perform the appropriate scan tool control function:
    • {If available} Starter Motor Relay - On and Off
    • {If available} Starter Relay - On and Off

      Verify the test lamp turns On and Off.

    • If the test lamp does not turn On 
    1. Disconnect the component: K20 Engine Control Module
    2. Disconnect the component: T19 Power Supply Transformer
    3. Test for less than 2 ohms between the test points: Control Circuit @ K20 Engine Control Module & KR27 Starter Relay Terminal 86
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: K20 Engine Control Module
    • If the test lamp is always On 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Disconnect the electrical connector: K20 Engine Control Module
    3. Disconnect the component: T19 Power Supply Transformer
    4. Test for infinite resistance between the test points: Control circuit terminal 86 @ Relay Socket & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: K20 Engine Control Module
    • Go to next step: If the test lamp turns On and Off 
  8. Verify a test lamp turns On between the test points: B+ circuit terminal 30 & 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: B+ circuit terminal 30 @ Relay Socket & 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: B+ circuit terminal 30 & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    3. Disconnect the electrical connector: X1 @ M64 Starter Motor
    4. Test for infinite resistance between the test points: Control circuit terminal 87 @ Relay Socket & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    5. Replace the component: M64 Starter Motor
    • Go to next step: If the test lamp turns On 
  9. Momentarily connect a 30 A fused jumper wire between the test points: B+ circuit terminal 30 & Control circuit terminal 87

    Verify the component does not turn On and Off when connecting and disconnecting the jumper wire: M64 Starter Motor

    • If the component turns On and Off 

      Test or replace the component: KR27 Starter Relay

    • Go to next step: If the component does not turn On and Off 
  10. Ignition/Vehicle & All vehicle systems - Off
  11. Install the component: KR27 Starter Relay
  12. Disconnect the electrical connector: X1 @ M64 Starter Motor
  13. Connect a test lamp between the test points: Control circuit terminal 1 & Ground
  14. Ignition - On/Vehicle - In Service Mode
  15. Perform the appropriate scan tool control function:
    • {If available} Starter Motor Relay - On and Off
    • {If available} Starter Relay - On and Off

      Verify the test lamp turns On and Off.

    • If the test lamp is always Off 

      Repair the open/high resistance in the circuit: Control Circuit

    • If the test lamp is always On 

      Repair the short to voltage on the circuit: Control Circuit

    • Go to next step: If the test lamp turns On and Off 
  16. Test or replace the component: M64 Starter Motor
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