Squib – Function, Symptoms, Types, Diagnosis, and Possible DTCs
The Squib is the electrical igniter inside an airbag module or seat belt pretensioner. When the Airbag Control Module (ACM/RCM/SDM/ORC) detects a severe collision, it sends a precisely controlled electrical current to the squib. The squib ignites the inflator, causing the airbag to deploy or the pretensioner to activate within milliseconds.
What Is a Squib?
Main Functions
- Receives the deployment signal from the SRS control module.
- Ignites the airbag inflator.
- Activates the seat belt pretensioner.
- Operates only during a qualifying collision.
Types of Squibs
- Driver Airbag Squib
- Passenger Airbag Squib
- Side Airbag Squib
- Curtain Airbag Squib
- Knee Airbag Squib
- Seat Belt Pretensioner Squib
Simple Circuit Diagram
+----------------------+
| Airbag Control Module|
+----------------------+
│
Deployment Signal
│
▼
+----------------------+
| Squib |
+----------------------+
│
▼
Airbag Inflator
Pretensioner
Common Symptoms of a Fault
- Airbag warning light ON.
- Open circuit or short circuit DTCs.
- High or low deployment loop resistance.
- SRS system disabled.
Possible Diagnostic Trouble Codes (DTCs)
- B0010–B0015 – Driver Airbag Squib Circuit
- B0020–B0028 – Passenger Airbag Squib Circuit
- B0030–B0040 – Pretensioner Squib Circuit
- B0051–B0053 – Deployment Loop Fault
- Manufacturer-specific Squib DTCs
Diagnosis Tips
- Read SRS codes using a professional scan tool.
- Inspect connectors and wiring for damage.
- Check the clockspring if the driver airbag squib is affected.
- Never apply battery voltage directly to a squib.
- Follow the manufacturer's approved SRS testing procedures.
Important Safety Note
A squib is a pyrotechnic device and can deploy an airbag or pretensioner if handled incorrectly. Never measure squib resistance directly with a standard multimeter unless the manufacturer specifically allows it. Always disconnect the battery and wait the recommended time before servicing any SRS component.
Frequently Asked Questions
What does a squib do?
It converts the electrical deployment signal into the ignition needed to activate the airbag inflator or seat belt pretensioner.
Can a faulty squib turn on the airbag warning light?
Yes. An open circuit, short circuit, or abnormal resistance in the squib circuit commonly triggers the SRS warning light.
Can a squib be repaired?
No. Squibs are not repairable. If defective or deployed, the affected airbag module or pretensioner must be replaced.