B1140

Code

Generic B — Body

Airbag Control Module Internal Fault

Brand: Generic

Type: B — Body

Views: UK: 21 EN: 25 RU: 19

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Internal electronic/component failure inside the airbag control module
Corrupted or erased module memory/software
Damage from prior deployment (module deployed or crash-damaged)
Water ingress, corrosion or physical damage to the module or connector
Insufficient or unstable power/ground to the module (low battery, blown fuse, poor ground)
Communication bus faults (CAN/LIN) or network interference

Symptoms

SRS/Airbag warning light illuminated and stays on
Possible additional SRS or network communication codes present
Airbag system disabled or partially disabled (seatbelt pretensioners may not function)
Scanner shows module internal error, fails to communicate or cannot be cleared
Intermittent or persistent loss of communication with the restraint module

What to check

Read all SRS and network codes with an appropriate scan tool (record freeze frame and stored events)
Visually inspect module and connectors for water, corrosion, bent pins, or physical damage
Check SRS fuses and related ignition power circuits
Verify battery voltage with key on and engine off (stable 12–14.5 V) and check for voltage dips
Verify good ground at module (measure resistance to chassis ground, should be very low)
Check CAN/LIN bus presence and idle voltages with a scan tool or oscilloscope

Signal parameters

Module supply voltage (expected ~12–14.5 V with engine running/charging)
Ground continuity (expected very low resistance, typically
CAN bus idle voltages ~2.5 V on CAN_H and CAN_L differential behavior present
Squib circuit resistance per manufacturer spec (open circuit indicates broken wire; near-short indicates short to ground)
Module wake/diagnostic response on OBD tool (module should enumerate and return status data)
Presence/absence of stored crash or deployment flags in module memory

Diagnostic algorithm

Safety first: follow manufacturer SRS safety procedures. Disconnect the negative battery terminal and wait the recommended time before touching SRS components.
Scan and record all SRS and network codes, freeze frame data, and module status using an OEM-capable scan tool.
Visually inspect the airbag control module, mounting area and connectors for signs of water intrusion, corrosion, impact damage or burnt components.
Check and verify all related fuses and relays for the airbag system; replace any blown fuses and retest.
Reconnect battery (if removed) and verify stable supply voltage at the module with ignition ON; check ground continuity to chassis.
Inspect and backprobe module connectors: check CAN_H/CAN_L voltages and look for proper bus activity (use scope or bus monitor tool).
Check continuity and resistance of squib circuits only per manufacturer procedure (do not short or seat-test squibs). If resistance is out of spec, trace wiring and connectors.
If power/ground and communications are good, attempt module reinitialization or reflash of SRS software using OEM diagnostic equipment (may clear memory corruption).
If module remains nonfunctional or reports internal faults after software attempts, replace the airbag control module with a new or OEM remanufactured unit.
After replacement, perform required programming/coding and clear crash/deployment flags per manufacturer procedure. Re-scan and verify the SRS system status and that the airbag light is extinguished.
If fault persists after replacement and programming, inspect vehicle wiring harness and network for intermittent shorts, opens or module-to-module communication issues.

Likely causes

Module suffered internal hardware failure (age, thermal stress, manufacturing defect)
Water or corrosion at module connector causing intermittent faults
Module memory corrupted after battery drain or crash event
Power/ground fault (blown SRS fuse, battery low, poor chassis ground)
Previous airbag deployment left module in a locked/faulted state

Fault status

⚠️ Status

Airbag control module internal fault — internal electronics or memory failure detected. SRS functions may be disabled until module is repaired or replaced and properly programmed.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours