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Circuit/System Testing

Diagnostic A

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR73 ignition main relay. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 85 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the circuit fuse is OK 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the B+ 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 OK and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF. repair the short to ground on the circuit
    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, replace the KR73 ignition main relay.
    • If the test lamp illuminates 
  5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  6. Verify the test lamp turns ON and OFF when commanding the run/crank relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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
    3. 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 K9 body control module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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, replace the K9 body control module.
    • If the test lamp turns ON and OFF 
  7. Verify that a test lamp does not illuminate between the ignition circuit terminal 87and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the ignition circuit.

    • If the test lamp does not illuminate 
  8. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 30 and the ignition control circuit terminal 87.
  9. Verify the device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    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
    3. 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, replace the device.
    • If the device activates 
  10. Test or replace the KR73 ignition main relay.

Diagnostic B

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR72B ignition 1 relay. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 85 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the circuit fuse is OK 
    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 OK and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF. repair the short to ground on the circuit
    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, replace the KR72B ignition 1 relay.
    • If the test lamp illuminates 
  5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  6. Verify the test lamp turns ON and OFF when commanding the relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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
    3. 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 K9 body control module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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, replace the K9 body control module.
    • If the test lamp turns ON and OFF 
  7. Verify that a test lamp does not illuminate between the ignition circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the ignition circuit

    • If the test lamp does not illuminate 
  8. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
  9. Verify device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    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
    3. 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, replace the device.
    • If the device activates 
  10. Test or replace the KR72B ignition 1 relay.

Diagnostic C

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR75 engine controls ignition relay, ignition ON.
  2. Verify a test lamp illuminates between the B+ circuit terminal 30 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 B+ 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 B+ circuit and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance, test or replace the KR75 engine controls ignition relay.
    • If the test lamp illuminates 
  3. Verify a test lamp illuminates between the B+ 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 B+ circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
    • If the test lamp illuminates 
  4. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
  5. Verify the test lamp turns ON and OFF when commanding the engine controls ignition relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K20 engine 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 K20 engine control module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K20 engine 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 K20 engine control module.
    • If the test lamp turns ON and OFF 
  6. Verify a test lamp does not illuminate between the ignition circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the circuit.

    • If the test lamp does not illuminate 
  7. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
  8. Verify device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    2. Test for infinite resistance between the ignition circuit terminal 87 and ground.
      • If less than infinite resistance, repair the short to ground on the circuit.
      • If infinite resistance
    3. 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, replace the device.
    • If the device activates 
  9. Test or replace the KR75 engine controls ignition relay.

Diagnostic D

  1. Ignition OFF and all vehicle systems OFF, disconnect the KR76 retained accessory power relay. It may take up to 2 minutes for all vehicle systems to power down.
  2. Test for less than 10 Ω between the ground circuit terminal 85 and ground.
    • If 10 Ω or greater 
    1. Ignition OFF.
    2. Test for less than 2 Ω in the ground circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, repair the open/high resistance in the ground connection.
    • If less than 10 Ω 
  3. Ignition ON.
  4. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
    • If the test lamp does not illuminate and the circuit fuse is OK 
    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 OK and there is voltage at the fuse.
    • If the test lamp does not illuminate and the circuit fuse is open 
    1. Ignition OFF. repair the short to ground on the circuit
    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, replace the KR76 retained accessory power relay.
    • If the test lamp illuminates 
  5. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
  6. Verify the test lamp turns ON and OFF when commanding the accessory/retained accessory power relay ON and OFF with a scan tool.
    • If the test lamp is always OFF 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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
    3. 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 K9 body control module.
    • If the test lamp is always ON 
    1. Ignition OFF, disconnect the harness connector at the K9 body 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, replace the K9 body control module.
    • If the test lamp turns ON and OFF 
  7. Verify that a test lamp does not illuminate between the ignition circuit terminal 87 and ground.
    • If the test lamp illuminates 

      Repair the short to voltage on the ignition circuit

    • If the test lamp does not illuminate 
  8. Ignition ON, connect a 3 A fused jumper wire between the B+ circuit terminal 30 and the ignition circuit terminal 87.
  9. Verify device is activated.
    • If the device does not activate 
    1. Ignition OFF, disconnect the harness connector at the device.
    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
    3. 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, replace the device.
    • If the device activates 
  10. Test or replace the KR76 retained accessory power relay.
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