B004B: Third Row Right Frontal Stage 3 Deployment Control

What it means

The restraint control module monitors the stage 3 deployment circuit for the third-row right frontal airbag. It sets this code when it detects an electrical fault in that circuit, such as an open, short, or resistance outside its expected range.

At a glance

• Usually lights the airbag (SRS) or body-system warning light

How it works

The restraint control module monitors stage 3 of the third-row right frontal airbag's deployment circuit. B004B sets when this particular stage 3 circuit has an electrical fault, such as an open, short, or resistance outside the expected range.

Common causes

Most likely first.

1. Open or high resistance in the stage 3 inflator circuit
2. Shorted or damaged wiring
3. Loose or corroded connector
4. Fault in the restraint control module

Symptoms

• Warning light or symbol related to the affected system
• Comfort or safety function impaired

How to diagnose it

1. Use an SRS-capable scan tool to capture B004B's subfault and event data, and establish whether the stage 3 fault is current or intermittent.
2. With the vehicle safely powered down according to the manufacturer, inspect the third-row right frontal stage 3 wiring and connectors for damage, corrosion, poor seating, or previous repairs.
3. Follow the manufacturer's wiring diagram and SRS-safe test procedure to check the stage 3 circuit for an open or short.
4. Check stage 3 circuit resistance and connector terminal contact against the specified procedure and specification; do not measure across the inflator unless expressly permitted.
5. If the circuit passes, use the manufacturer's diagnostic procedure to isolate a faulty airbag module from a restraint control module fault.

Common fixes

• Repair damaged wiring in the third-row right frontal stage 3 circuit.
• Repair or reseat a loose or corroded stage 3 connector using the approved SRS method.
• Replace the airbag module if the stage 3 deployment circuit fails the manufacturer's test.
• Repair or replace the restraint control module if circuit and airbag-module checks pass and module diagnosis confirms the failure.

Can I keep driving?

Stage 3 of the third-row right frontal airbag may not deploy as intended in a crash; arrange prompt SRS diagnosis and avoid using that seating position until repaired. Follow the manufacturer's SRS safety procedure before working near the airbag circuit.