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DTC B2577: ALC Headlight Relay Output Short To Ground/Open: Testing

  1. If BFC diagnostic system check was performed, go to next step. If BFC diagnostic system check was not performed, see procedures in BFC DIAGNOSTIC SYSTEM CHECK  .
  2. Remove ALC headlight relay from underhood wiring harness junction block. Replace ALC headlight relay with a known-good relay. Using scan tool, enable ALC headlight relay. If automatic lighting control operates properly, go to step 10). If automatic light control does not operate properly, go to next step.
  3. Reconnect ALC headlight relay. Back out underhood wiring harness junction block Brown 68-pin Brown connector C3, terminal C11 (Pink/White wire). Using DVOM, check voltage between underhood wiring harness junction block connector C3, terminal C11 (Pink/White wire) and ground. If battery voltage exists, go to step 5). If battery voltage does not exist, go to next step.
  4. Replace underhood wiring harness junction block. Go to step 10).
  5. Disconnect BFC Gray 16-pin connector C1, terminal A1 (Pink/White wire). Using DVOM, check resistance between BFC harness connector C1, terminal A1 (Pink/White wire) and ground. If resistance is infinite, go to step 7). If resistance is not infinite, go to next step.
  6. Repair short to ground in Pink/White wire between BFC connector C1 and underhood wiring harness junction block connector C3. Go to step 10).
  7. Using DVOM, check resistance between BFC harness connector C1, terminal A1 (Pink/White wire) and underhood wiring harness junction block harness connector C3, terminal C11 (Pink/White wire). If resistance is 0-2 ohms, go to step 9). If resistance is not 0-2 ohms, go to next step.
  8. Repair open in Pink/White wire between BFC connector C1 and underhood wiring harness junction block connector C3. Go to step 10).
  9. Replace BFC. See REMOVAL & INSTALLATION  . Go to next step.
  10. Clear DTCs. Perform BFC DIAGNOSTIC SYSTEM CHECK  .


  1. If BFC diagnostic system check was performed, go to next step. If BFC diagnostic system check was not performed, see procedures in BFC DIAGNOSTIC SYSTEM CHECK  .
  2. Remove ALC headlight relay from underhood wiring harness junction block. Replace ALC headlight relay with a known-good relay. Using scan tool, enable ALC headlight relay. If automatic lighting control operates properly, go to step 10). If automatic light control does not operate properly, go to next step.
  3. Reconnect ALC headlight relay. Back out underhood wiring harness junction block Brown 68-pin Brown connector C3, terminal C11 (Pink/White wire). Using DVOM, check voltage between underhood wiring harness junction block connector C3, terminal C11 (Pink/White wire) and ground. If battery voltage exists, go to step 5). If battery voltage does not exist, go to next step.
  4. Replace underhood wiring harness junction block. Go to step 10).
  5. Disconnect BFC Gray 16-pin connector C1, terminal A1 (Pink/White wire). Using DVOM, check resistance between BFC harness connector C1, terminal A1 (Pink/White wire) and ground. If resistance is infinite, go to step 7). If resistance is not infinite, go to next step.
  6. Repair short to ground in Pink/White wire between BFC connector C1 and underhood wiring harness junction block connector C3. Go to step 10).
  7. Using DVOM, check resistance between BFC harness connector C1, terminal A1 (Pink/White wire) and underhood wiring harness junction block harness connector C3, terminal C11 (Pink/White wire). If resistance is 0-2 ohms, go to step 9). If resistance is not 0-2 ohms, go to next step.
  8. Repair open in Pink/White wire between BFC connector C1 and underhood wiring harness junction block connector C3. Go to step 10).
  9. Replace BFC. See REMOVAL & INSTALLATION  . Go to next step.
  10. Clear DTCs. Perform BFC DIAGNOSTIC SYSTEM CHECK  .
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