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Home >> Chevrolet >> 2006 >> TrailBlazer 6.0 H, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 249 (Lighting Systems) >> Diagnostic Information and Procedures >> DTC B2575 >> Component Testing >> Relay Testing
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Relay Testing

WARNING: This page is about a different car, the 2007 Pontiac Torrent and 2007 Chevrolet Equinox. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the headlamp relay.
  2. Test for 65 to 95 ohms of resistance 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 less than infinite resistance, replace the relay.
  4. Test for less than 2 ohms of resistance between terminals 30 and 87A.
    • If greater than 2 ohms, replace the relay.
  5. Install a 15-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Measure for less than 2 ohms of resistance between terminals 30 and 87.
    • If greater than 2 ohms, replace the relay.