Damaged or disconnected wiring harness at the third row right airbag connector; Corroded or loose electrical connector terminals at the airbag or RCM; Open or shorted airbag squib (deployment circuit) inside the third row right airbag module; Faulty clock spring or wiring pass-through if the circuit routes through a moving component (less common for third row); Internal failure in the restraint control module (RCM); Aftermarket accessories or previous repairs that disturbed the SRS wiring; Water intrusion or physical damage to the wiring in the third row area

DTC codes / B00xx · Airbags, seats, doors, lights and comfort systems / B004B

B004BThird Row Right Frontal Stage 3 Deployment Control

Q: What does code B004B mean?

Third Row Right Frontal Stage 3 Deployment Control. B004B indicates that the restraint control module (RCM) has detected a fault in the deployment circuit for the third row right frontal airbag stage 3. The module monitors the circuit's resistance and continuity and sets this code when the signal falls outside the expected range, which can prevent that airbag stage from deploying correctly in a crash.

B004B indicates that the restraint control module (RCM) has detected a fault in the deployment circuit for the third row right frontal airbag stage 3. The module monitors the circuit's resistance and continuity and sets this code when the signal falls outside the expected range, which can prevent that airbag stage from deploying correctly in a crash.

SystemBody

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

Airbag warning light illuminated on the instrument cluster
SRS (Supplemental Restraint System) message displayed on the driver information center
Often no symptoms besides the warning light
The third row right airbag may be disabled and will not deploy in a collision
Other restraint system codes may be stored alongside B004B
In some vehicles, a chime or reminder to service the restraint system

Common causes, most likely first

Damaged or disconnected wiring harness at the third row right airbag connector
Corroded or loose electrical connector terminals at the airbag or RCM
Open or shorted airbag squib (deployment circuit) inside the third row right airbag module
Faulty clock spring or wiring pass-through if the circuit routes through a moving component (less common for third row)
Internal failure in the restraint control module (RCM)
Aftermarket accessories or previous repairs that disturbed the SRS wiring
Water intrusion or physical damage to the wiring in the third row area

How to diagnose and fix it

Scan all modules for codes and record freeze-frame data to confirm B004B is current and not history
Visually inspect the third row right airbag connector and wiring for damage, corrosion, or loose pins
Disconnect the battery and wait the manufacturer-specified time, then measure resistance across the airbag squib to check for an open or short
Check continuity and resistance of the wiring harness between the airbag connector and the RCM, looking for opens or shorts to ground
Substitute a known-good airbag simulator at the connector to isolate whether the fault is in the airbag or the harness/RCM
If the harness and airbag test good, diagnose the RCM with a capable scan tool and follow manufacturer pinpoint tests
Clear codes and verify the repair with a scan tool and by cycling the ignition

Before you replace the third row airbag

A common mistake is replacing the airbag when the real problem is a corroded connector or chafed wire under the third row seat, so always inspect the harness first.
B004B can be set by a low battery or voltage spike during service, so check for history codes and verify the battery condition before condemning parts.
The RCM may store this code if the airbag connector was unplugged with the ignition on, so always disconnect the battery before working on SRS components.
Aftermarket seat covers or cargo accessories can pinch the third row wiring, causing intermittent faults that only appear when the seats are folded or loaded.
Some vehicles require the RCM to be configured or programmed after replacement, and a used module may not work without proper initialization.

Can I keep driving with B004B?

The vehicle is not safe to drive because the third row right frontal airbag may not deploy in a crash, so have the fault diagnosed and repaired before carrying passengers in that seat. Avoid any impact to the third row area and do not attempt to repair SRS wiring without proper training.

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.