Circuit/System Testing

2009 Chevrolet Tahoe Base, 4.8 CSECTION Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect the harness connector at the adjustable pedal switch.
  2. Ignition ON, test for B+ between the appropriate B+ reference circuit listed below and ground:
    • X88/Z88 - terminal 11
    • Z75 - terminal 5
    • If greater than the specified range, test the B+ reference circuit for a short to voltage. If the circuit tests normal, replace the MSM.
    • If less than the specified range, test the B+ reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  3. Verify the scan tool Pedal Forward Switch parameter is Inactive.
    • If not the specified value, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • X88/Z88 - terminal 12
    • Z75 - terminal 6
  4. Verify the scan tool Pedal Aft Switch parameter is Inactive.
    • If not the specified value, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the MSM.
    • X88/Z88 - terminal 10
    • Z75 - terminal 4
  5. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and B+. The scan tool Pedal Forward Switch parameter should be Active.
    • X88/Z88 - terminal 12
    • Z75 - terminal 6
    • If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  6. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and B+. The scan tool Pedal Aft Switch parameter should be Active.
    • X88/Z88 - terminal 10
    • Z75 - terminal 4
    • If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
  7. If all circuits test normal, test or replace the adjustable pedal switch.
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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.