B2101 Active Headrest Switch Circuit Fault
The B2101 code indicates that the Body Control Module (BCM) or Driver Seat Module (DSM) has detected a fault in the active headrest switch circuit, typically an open circuit, short to ground, or short to battery voltage. This system adjusts the headrest position during a rear-end collision to reduce whiplash injuries. The fault may prevent the active headrest from deploying properly, compromising occupant safety.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty active headrest switch
- Damaged wiring or corroded connectors in the switch circuit
- Defective seat control module (DSM/BCM)
- Short to ground or voltage in the switch signal circuit
3. Symptoms You Will Notice
- Active headrest inoperative or stuck in one position
- Airbag warning light or service active headrest message on the dash
- No headrest movement during rear impact test (if applicable)
4. Step-by-Step Diagnosis
Scan the BCM/DSM for B2101 and related codes
Visually inspect the headrest switch, wiring, and connectors for damage or corrosion
Test the switch continuity and resistance with a multimeter
Check for shorts to ground or battery voltage in the signal circuit
If all else is good, test or replace the seat control module
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle can be driven, but the active headrest may not deploy in a rear-end collision, increasing the risk of whiplash injury. It is recommended to have the issue diagnosed and repaired promptly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the switch, wiring, or module needs replacement. Diagnostic fees are usually around $100.