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Circuit/System Testing

NOTE:

Use the schematics and connector end views to identify the following:

  • The master control module and the LIN devices on the same LIN serial data circuit
  • The master control module's LIN serial data circuit terminal and the LIN device's B+, ignition, ground, and LIN serial data circuit terminals
  1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connector at a LIN device that is not communicating. It may take up to 10 min for all vehicle systems to power down.
  2. Test for less than 10 Ω between each ground circuit terminal and ground.
    • If 10 Ω or greater 
    1. Ignition/Vehicle 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/Vehicle In Service Mode.
  4. If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition/Vehicle OFF, remove the test lamp.
    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/Vehicle OFF, remove the test lamp.
    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, replace the disconnected LIN device.
    • If the test lamp illuminates 
  5. If equipped, verify a test lamp illuminates between each ignition circuit terminal and ground.
    • If the test lamp does not illuminate and the circuit fuse is good 
    1. Ignition/Vehicle OFF, remove the test lamp.
    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/Vehicle OFF, remove the test lamp.
    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 disconnected LIN device.
    • If the test lamp illuminates 
  6. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which is controlled by a control module, and ground.
    • If the test lamp does not illuminate 
    1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the control module that controls the ignition 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
    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 control module that controls the ignition circuit.
    • If the test lamp illuminates 
  7. Ignition/Vehicle OFF, disconnect all LIN devices that share the same LIN serial data circuit, ignition ON/Vehicle In Service Mode.
    8. NOTE:

    For accurate voltage reading, disconnect the battery charger prior to performing the following test step.

  8. Test for 2 - 12 V between the LIN serial data circuit terminal and ground.
    • If less than 2 V 
    1. Ignition/Vehicle OFF, disconnect the harness connector at the control module setting the DTC.
    2. Test for infinite resistance between the serial data 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 serial data circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω
    4. Reconnect the control module that set the DTC, ignition ON/Vehicle In Service Mode.
    5. Test for 2 - 12 V between the LIN serial data circuit terminal and ground.
      • If less than 2 V, replace the control module setting the DTC.
      • If greater than 2 V, replace the LIN device that causes a current DTC to set when connected.
    • If greater than 12 V 
    1. Ignition/Vehicle OFF, disconnect the harness connector at the control module setting the DTC, ignition ON/Vehicle In Service Mode.
    2. Test for less than 1 V between the serial data circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition/Vehicle OFF, reconnect the control module that set the DTC, ignition ON/Vehicle In Service Mode.
    4. Test for 2 - 12 V between the LIN serial data circuit terminal and ground.
      • If greater than 12 V, replace the control module setting the DTC.
      • If less than 12 V, replace the LIN device that causes a current DTC to set when connected.
    • If between 2 - 12 V 
  9. Replace the disconnected LIN device.
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