Circuit/System Testing (ECM)

2006 Chevrolet Suburban K1500, 5.3 ZSECTION Circuit/System Testing (ECM)
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 volts.
  2. Ignition OFF, disconnect the harness connectors at the ECM.
  3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 30 seconds. Test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground.
    • Terminal 73 X1 (LZ4)
    • Terminal 73 X2 (LAT, LE5, LY7)
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 20 X1 and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  5. Ignition OFF, connect a 3A fused jumper between the appropriate PWR/TRN relay control circuit terminal listed below and ground.
    • Terminal 13 X1 (LE5)
    • Terminal 40 X1 (LY7)
    • Terminal 59 X1 (LZ4)
    • Terminal 40 X2 (LAT)
  6. Ignition ON, verify that a test lamp illuminates between the appropriate ignition circuit terminals listed below and ground:
    • Terminal 3 X1 (LE5)
    • Terminal 18 X1 (LAT, LY7, LZ4)
    • Terminal 19 X1 (LAT, LE5, LY7, LZ4)
    • Terminal 47 X1 (LZ4)
    • Terminal 73 X1 (LE5)
    • Terminal 13 X2 (LAT, LY7)
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  7. If all circuits test normal, replace the ECM.
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When to See a Mechanic

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

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