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HOMESERVICE MANUALSCHEVROLET2019TAHOE LS, 4WD, GAS/ETHANOLREPAIR AND DIAGNOSIS (SINGLE PAGE)ACCESSORIES & EQUIPMENTCOMMUNICATION DEVICESDATA COMMUNICATION SYSTEM - DIAGNOSTIC INFORMATION AND PROCEDURESDIAGNOSTIC INFORMATION AND PROCEDURESDTC U2160-U2231CIRCUIT/SYSTEM TESTING
2019 Chevrolet Tahoe LS, 4WD, Gas/Ethanol

Circuit/System Testing

2019 Chevrolet Tahoe LS, 4WD, Gas/EthanolSECTION Circuit/System Testing
NOTE:

Use the schematics and connector end views to identify the device's ground, B+, ignition, accessory wakeup 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. Disconnect all the harness connectors at the device that is not communicating. It may take up to 2 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 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.
    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, replace the disconnected device.
    • Go to next step: If the test lamp illuminates 
  5. Ignition ON.
  6. 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.
    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.
    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 device.
    • Go to next step: If the test lamp illuminates 
  7. Ignition ON.
  8. 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 OFF, 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.
      • Go to next step: 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.
    • Go to next step: If the test lamp illuminates 
    9. NOTE:

    This test step is only applicable to a low speed GMLAN device.

  9. Test for less than 4.5 V between each low speed GMLAN serial data circuit terminal and ground.
    • Go to next step: If less than 4.5 V 
  10. 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.
  11. Test for less than 2 Ω in each of the serial data circuits end to end between the device harness connector and the X84 Data Link Connector terminals listed below.
    • Low speed GMLAN serial data circuit terminal 1
    • High speed GMLAN serial data circuit terminal 6 or 14
    • Mid speed GMLAN serial data circuit terminal 3 or 11
    • Chassis high speed GMLAN serial data circuit terminal 12 or 13
    • Object high speed GMLAN serial data circuit terminal 3 or 11
    • If 2 Ω or greater 

      Repair the open/high resistance in the serial data circuit between the non communicating device and the device setting the DTC or a serial data splice pack.

    • Go to next step: If less than 2 Ω 
    12. NOTE:

    The following test step is only applicable to a high speed GMLAN device with 2 pairs of serial data circuits or a high speed GMLAN device with an internal terminating resistor.

  12. Test for 110 - 130 Ω between each pair of high speed GMLAN serial data circuits.
    • Go to next step: If between 110 - 130 Ω 
  13. Replace the device that is not communicating.
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.