LEMON Manuals: Even more car manuals for everyone
Home >> Saab >> 2010 >> 9-5 >> Repair and Diagnosis >> Electrical >> Horns >> Lighting And Signaling Systems >> Fault diagnosis, fault codes >> DTC B257B: Lighting Control Switch Signal >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch.
  2. Ignition ON, test for B+ between the 12 V reference circuit terminal 1 and ground.
  3. If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
  4. Ignition ON, test for less than 0.3 V between dimming signal circuit terminal 12 and ground.
  5. If greater than the specified range, test the dimming signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module.
  6. Reconnect the harness connector at the S30 Headlamp Switch.
  7. Dim the interior backlighting with the S30 Headlamp Switch.
  8. Disconnect the harness connector at the S30 Headlamp Switch.
  9. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the voltage reference circuit terminal 1. The interior backlighting should now be dimmed.
  10. If the interior backlighting is not dimmed, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
  11. If all circuits test normal, replace the S30 Headlamp Switch.
scientia non olet · About LEMON Manuals