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Home >> Cadillac >> 2009 >> XLR Base >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel System Displays & Gauges >> Diagnostic Information and Procedures >> DTC B3621 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the HUD switch.
  2. Test for less than 5.0 ohm between the low reference circuit terminal 1 and ground.
    • If greater than the specified range, test the low reference circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Adjust Display Down Switch parameter is Inactive.
    • If not Inactive, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the HUD.
  4. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Adjust Display Down Switch parameter is Active.
    • If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HUD.
  5. If all circuits test normal, test or replace the HUD switch.
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