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DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B00D4

B00D4Restraint System Malfunction Audible Indicator

B00D4 indicates that the restraint control module (RCM) has detected a fault in the audible warning circuit that normally provides chimes or buzzers for seatbelt reminders and airbag system warnings. The module monitors the speaker or sounder circuit for opens, shorts, or excessive resistance and sets this code when the signal is outside the expected range.

SystemBody
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • No chime or buzzer when the key is turned on or when a seatbelt is unbuckled
  • Airbag warning light illuminated on the instrument cluster
  • Seatbelt reminder light may stay on longer than usual or not illuminate at all
  • Intermittent or distorted audible warnings
  • Often no symptoms besides the warning light if the fault is in a separate sounder circuit

Common causes, most likely first

  1. Failed audible indicator speaker or sounder
  2. Open or shorted wiring between the restraint control module and the sounder
  3. Corroded or loose electrical connector at the sounder or module
  4. Faulty restraint control module (internal driver circuit failure)
  5. Blown fuse or poor ground connection for the sounder circuit
  6. Water intrusion or physical damage to the sounder or wiring harness

How to diagnose and fix it

  1. Verify the code with a scan tool and check for any related body or restraint codes
  2. Inspect the sounder and its connector for corrosion, damage, or loose pins
  3. Test the sounder with a known-good substitute or apply battery voltage briefly to confirm operation
  4. Measure resistance and continuity of the wiring between the restraint control module and the sounder
  5. Check the fuse and ground connections for the sounder circuit
  6. If wiring and sounder are good, test the output signal from the restraint control module with a multimeter or oscilloscope
  7. Replace the faulty component (sounder, wiring, or module) and clear the code to verify repair

Hidden causes of a silent chime

  • A faulty door ajar switch or seatbelt buckle sensor can trigger the chime circuit and set this code indirectly, so check those inputs before condemning the sounder.
  • Some vehicles use the same sounder for multiple warnings, and a failure in one trigger circuit can cause the module to set B00D4 even though the speaker itself is fine.
  • The restraint control module often logs this code when battery voltage is low during cranking, so clear the code and retest after ensuring a healthy battery.
  • Aftermarket audio or alarm installations that tap into the chime circuit are a common cause of this code on older vehicles.
  • A sounder that tests good on the bench may still fail under load, so always test it in the vehicle with the module connected.

Can I keep driving with B00D4?

The vehicle remains safe to drive because the audible warning is a convenience feature, but you should not ignore the airbag warning light if it is also illuminated. Have the system diagnosed soon to restore the seatbelt reminder and any associated safety warnings.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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