What Does B2101 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an electrical fault in the power adjustable headrest switch circuit. The BCM monitors the switch inputs and has identified an open circuit, short circuit, or abnormal resistance value that falls outside acceptable parameters. This code typically appears in vehicles equipped with power-adjustable or active headrest systems.
Common Causes
35%
Faulty headrest adjustment switch with internal contact failure or wear
30%
Damaged or corroded wiring harness between headrest switch and BCM
20%
Poor electrical connection at switch connector due to corrosion or pin damage
10%
Short circuit to ground or power in headrest switch circuit wiring
5%
Failed Body Control Module with faulty input circuitry
Diagnostic Steps
1
Step 1: Perform visual inspection of the headrest switch for physical damage, burnt contacts, or moisture intrusion. Check for obvious damage to switch housing and operating feel.
2
Step 2: Disconnect the headrest switch connector and inspect for corrosion, pushed-back pins, or contamination. Clean terminals with electrical contact cleaner if corrosion is present.
3
Step 3: With switch disconnected, use a digital multimeter to measure resistance across switch terminals while actuating the switch through all positions. Compare readings to manufacturer specifications (typically 0-5 ohms closed, infinite open).
4
Step 4: Check continuity and resistance of wiring between the headrest switch connector and BCM connector. Look for opens (infinite resistance), shorts to ground (0 ohms to chassis), or shorts to power (battery voltage present).
5
Step 5: With ignition on and switch connector attached, backprobe the switch signal and ground circuits with a multimeter or oscilloscope to verify proper voltage levels (typically 5V reference, switching to ground when activated).
6
Step 6: If all wiring and switch test normal, verify BCM ground connections are secure and test BCM input voltage at the module connector. Clear codes, perform switch actuation test, and verify repair by confirming code does not return.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an electrical fault in the power adjustable headrest switch circuit. The BCM monitors the switch inputs and has identified an open circuit, short circuit, or abnormal resistance value that falls outside acceptable...
The most common cause of B2101 (Head Rest Switch Circuit Failure) is: Faulty headrest adjustment switch with internal contact failure or wear
Typical repair costs for B2101 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or drivability and the vehicle is safe to continue operating. The power headrest adjustment feature will be inoperative, but this poses no immediate safety risk and repair can be scheduled at convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2101 to identify the root cause.
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Quick Info
Category
Body
System
Body Comfort and Convenience Systems
Difficulty
Type
Generic (SAE)
Recommended Tools
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