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Home >> Chevrolet >> 2011 >> Chevy Express H1500, Van Cargo >> Repair and Diagnosis >> External Pages >> Different car >> Section 1764 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P0526 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2010 GMC Savana Special, 2010 GMC Savana Camper Special, 2010 GMC Savana, 2010 Chevrolet RV Cutaway, and 2010 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the fan clutch harness at the cooling fan shroud.
  2. Test for less than 3 Ω between ground and the low reference circuit terminal C.
    • If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, test for 4.8-5.2 V between the 5-volt reference circuit terminal E and the low reference circuit terminal C.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Connect fused jumper wires between the harness and sensor pigtail connectors for the circuit terminals listed below:
    • 5-volt reference circuit terminal E
    • Low reference circuit terminal C
  5. Ignition ON, measure voltage between the signal circuit terminal D at the sensor pigtail connector and the 5-volt reference circuit jumper wire terminal, while rotating the cooling fan by hand. The voltage should toggle between approximately 5 V and 0 V.
    • If the voltage does not toggle correctly, test the circuits/connections in the pigtail harness. If the circuits test normal, replace the fan clutch.
  6. Leave the fused jumper wire from the previous step connected to the 5-volt reference circuit terminal E at the harness side of the connector. Momentarily touch opposite end of the jumper wire to the signal circuit terminal D of the harness connector, while observing the scan tool Fan Speed parameter. The parameter should display a speed above 0 RPM when the signal circuit is repeatedly toggled to 5 V.
    • If the Fan Speed parameter does not display a speed greater than 0 RPM, test the signal circuit for a short to ground, a short to voltage, or an open/high resistance. If the circuit tests normal, replace the ECM.
  7. If all circuits/connections test normal, replace the cooling fan clutch.
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