Circuit/System Testing

2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 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 at the B23 camshaft position sensor.
  2. Ignition OFF and all vehicle systems OFF, it may take 2 minutes for all vehicle systems to power down, test for less than 1 Ξ© on the camshaft position low reference circuit, terminal B, and ground.
    • If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.
  3. Ignition ON, test for 4.8-5.2 V between the camshaft position 5 V reference circuit terminal A and ground.
    • If less than the specified range, test the 5 V reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM.
    • If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  4. Ignition ON, test for 4.8-5.2 V between the camshaft position signal circuit terminal C and ground.
    • If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 ECM.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  5. Ignition OFF, connect a fused jumper wire to the camshaft position signal circuit terminal C.
  6. Ignition ON, momentarily touch the other the other end of the fused jumper wire to the battery negative post. The scan tool should show the Camshaft Position Active counter incrementing.
    • If the Camshaft Position Active counter increments, test or replace the B23 camshaft position sensor.
    • If the Camshaft Position Active counter does not increment, replace the K20 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.