Circuit/System Verification

2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Verification
WARNING: This page is about a different variant/trim than selected.
  1. Ignition ON with the engine OFF, command the Aux. Trans. Pump Speed to 50 percent with the scan tool. Attempt to maintain pump operation for at lease 60 seconds.
  2. Observe the aux. trans. fluid pump actual display and the aux. trans. fluid pump commanded displays with the scan tool. Actual pump speed should be maintained within 10 percent of commanded. The pump should not make excessive noise ro stall.
    • If the actual speed is within 10 percent of commanded speed an electrical fault condition is not currently present, if an aux. trans. fluid pump pressure fault is suspected, test the aux. trans. pump line pressure output. Refer to Line Pressure Check .
    • If the difference between actual and commanded speed is greater than 10 percent, the pump is noisy, or the pump stalls, proceed to Circuit/System Testing.
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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.