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Home › Chevrolet › 2017 › City Express LS › Repair and Diagnosis › Accessories & Equipment › Communication Devices › Data Communication System › Diagnostic Information And Procedures › DTC U1117: Lost Communication With Electronic Brake Control Module › Circuit/System Testing

Circuit/System Testing

NOTE:

Use the schematics and connector end views to identify the control module's ground, B+, ignition, accessory wake up serial data, serial data communication enable, and serial data circuit terminals.

  1. Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect all the harness connectors at the K17 Electronic Brake Control Module.
  2. Test for less than 10 Ω between each ground circuit terminal 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.
    • Go to next step: If less than 10 Ω 
  3. Ignition ON.
  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 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 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 control module.
    • Go to next step: 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 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 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 control module.
    • Go to next step: If the test lamp illuminates 
  6. Test for less than 4.5 V between each LAN serial data circuit terminal and ground.
    • Go to next step: If less than 4.5 V 
  7. Ignition OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.
  8. Test for greater than 100 Ω between each LAN serial data circuit terminal and ground.
    • Go to next step: If greater than 100 Ω 
  9. Disconnect the harness connectors at the control module setting the DTC.
  10. Test for less than 2 Ω in each of the LAN serial data circuits end to end between the two control modules.
    • If 2 Ω or greater 

      Repair the open/high resistance in the serial data circuit between the two control modules.

    • Go to next step: If less than 2 Ω 
  11. Replace the K17 Electronic Brake Control Module.
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