1997 Buick Century CustomFACTORY OEM SERVICE PROCEDURE

DTC B2805, RFA Programming/Diagnostic Mode Message Not Received: Testing

  1. If BCM diagnostic system check was performed, go to next step. If BCM diagnostic system check was not performed, go to BCM DIAGNOSTIC SYSTEM CHECK  .
  2. Turn ignition off. Attempt to enable transmitter programming/diagnostic mode. See appropriate REMOTE KEYLESS ENTRY SYSTEM article. If transmitter programming/diagnostic mode can be entered, go to next step. If transmitter programming/diagnostic mode cannot be entered, go to step 4).
  3. Exit transmitter programming/diagnostic mode by turning ignition switch to RUN position. Using scan tool, clear DTCs. Turn ignition off. Enable transmitter programming/diagnostic mode again. Check for DTCs. If DTC B2805 sets again, go to step 5). If DTC B2805 does not set again, system is operating properly.
  4. Using Remote Keyless Entry (RKE) transmitter, attempt to lock and unlock doors. If doors lock and unlock, go to step 7). If doors do not lock and unlock, go to step 6).
  5. Turn ignition off. Replace BCM. See REMOVAL & INSTALLATION  . Reprogram BCM. See BCM PROGRAMMING. Go to step 7).
  6. Using Device Control function on a Tech 2 scan tool, activate RFA link output. Using DVOM, check voltage between ground and BCM 32-pin connector C1 terminal C15 (Black wire). If reading is less than 2 volts, go to step 8). If reading is not less than 2 volts, go to step 5).
  7. Turn ignition off. Reinstall all components and connectors. Turn ignition on. Using scan tool, clear DTCs. Perform BCM DIAGNOSTIC SYSTEM CHECK  .
  8. Check for poor connections at RCDLR. If connections are okay, replace RCDLR. Go to step 7).
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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