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Home >> Chevrolet >> 2021 >> Suburban Z71 >> Repair and Diagnosis >> Body & Frame >> Towing Systems >> TRAILERING Systems >> Diagnostic Information and Procedures >> DTC U3003 (Trailer Lamp Control Module) >> Circuit/System Verification
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Circuit/System Verification

  1. Ignition/vehicle off
  2. NOTE:

    The battery voltage should stabilize after a few minutes of turning the ignition/vehicle Off.

  3. Test for 12.4 - 12.8 V between the battery posts.
    • Go to next step: If between 12.4 - 12.8 V 
  4. Start the engine and allow it to idle for 15 s.
  5. Turn all electrical accessories off.
  6. Test for 13.4 - 15 V between the battery posts.
    • Go to next step: If between 13.4 - 15 V 
  7. Refer to Circuit/System Testing