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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 66 (Engine Cooling System) >> Diagnostic Information and Procedures >> Cooling Fan Inoperative >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the series/parallel relay.
  2. Ignition ON, activate the cooling fan relay 1 with the scan tool. The fan should be OFF.
    • If the fan is activated, test the left fan ground circuit for a short to ground.
  3. Ignition OFF, disconnect the fan relays.
  4. Connect a 30A fused jumper between the normally-open switch contact terminals at the series/parallel relay connector in order to complete the left fan ground circuit. Leave this jumper in place for the remainder of this procedure.
  5. One at a time, connect a 30A fused jumper between the positive terminal at the battery and the fan voltage supply circuit terminal at the cool/fan 1 and the cool/fan relay connections and verify fan activation.
    • If the appropriate fan does not activate, test the fan voltage supply circuit for a short to ground or open/high resistance.
    • If the circuit tests normal, test the fan ground circuit for an open/high resistance.
    • If the circuits test normal, replace the fan.
  6. Ignition ON, connect a 30A fused jumper between the relay switch voltage supply circuit terminal and the fan voltage supply circuit terminal at the cool/fan 1 and the cool/fan relay connections and verify fan activation.
    • If the fan does not activate, test the relay switch voltage supply circuit for a short to ground or high resistance.
    • If the circuit tests normal and its fuse is open, test all connected components and replace as necessary.
  7. If the circuits and fans test normal, replace the relay.
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