Circuit/System Testing

2011 GMC Savana Special 4.8 ASECTION Circuit/System Testing
WARNING: This page is about a different variant/trim than selected.
  1. Engine idling, move the related harnesses/connectors of the B23 camshaft position sensor while monitoring the scan tool Camshaft Position Variance parameter. The Camshaft Position Variance parameter should not change when moving the harness/connectors.
    • If the above condition exists, repair the harness/connectors as necessary.
  2. Ignition OFF, inspect the B23 camshaft position sensor for correct installation.
    • If the B23 camshaft position sensor is loose, inspect the sensor and the O-ring for damage, and replace as necessary.
  3. Disconnect the harness connector at the B23 camshaft position sensor.
  4. Ignition OFF, all vehicle systems OFF, this may take 2 minutes, test for less than 5 Ξ© between the low reference circuit terminal 2 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  5. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
    • If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
    • 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 engine control module.
  6. Test for 4.8-5.2 V between the signal circuit terminal 1 and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 engine control module.
  7. If all circuits test normal, replace the B23 camshaft position sensor.
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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.