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Home >> Chevrolet >> 2006 >> Silverado 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1138 (Engine Cooling System) >> Diagnostic Information and Procedures >> DTC P2600-P2603 >> Component Testing

Component Testing

WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the auxiliary coolant pump relay.
  2. Test for 70-110 ohms between terminals 85 and 86.
    • If the resistance is not within the specified range, replace the relay.
  3. Test for infinite resistance between the following terminals:
    • 30 and 86
    • 30 and 87
    • 30 and 85
    • 85 and 87
    • If not the specified value, replace the relay.
  4. Connect a 20-amp fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay.
    • If greater than the specified range, replace the relay.