Circuit/System Testing

2006 Chevrolet Suburban C2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector of the stop lamp switch.
  2. Ignition ON, verify that a test lamp illuminates between the stop lamp switch voltage circuit terminal B and ground.
    • If the test lamp does not illuminate, test the stop lamp switch voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the RUN/CRANK Relay.
  3. Ignition OFF, disconnect the harness connectors of the BCM X5, ECM X1, TCM (if equipped), Power Take Off (PTO) module (if equipped) and Trailer Brake controller (if equipped).
  4. Ignition OFF, verify that a test lamp does not illuminate between the stop lamp switch harness terminal A and B+.
    • If the test lamp illuminates, test the brake switch signal circuit for a short to ground.
  5. Test for less than 1.0 ohm resistance between the stop lamp switch harness terminal A and one of the following:
    • ECM connector X1 terminal 83 for the 6.6L engine.
    • ECM connector X1 terminal 55 for the 4.3L engine.
    • ECM connector X1 terminal 9 for the 4.8L, 5.3L, 6.0L, 6.2L or 7.0L engines.
    • If resistance is not as specified, test the stop lamp switch circuit for an open/high resistance.
  6. Ignition ON, verify that a test lamp does not illuminate between the stop lamp switch TCC brake signal circuit terminal A and ground.
    • If the test lamp illuminates, test the brake switch signal circuit for a short to voltage.
  7. If all circuits test normal, test or replace the stop lamp switch. If the component and all circuit tests are normal, replace the ECM.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

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.