The blind spot detection system in your 2020 Chrysler 300 adds an extra layer of safety during lane changes. But when the system malfunctions—displaying a warning message or simply not working—you lose that valuable assistance and need to find out why.
How Blind Spot Monitoring Works
The Chrysler 300's Blind Spot Detection System (BSDS) uses radar sensors mounted in the rear bumper, typically one on each side. These sensors emit radar waves that detect vehicles in your blind spots and trigger warnings—both visual (indicator lights in the mirrors) and sometimes audible alerts when turning into an occupied lane.
Common Malfunction Symptoms
- Warning light stays illuminated on dashboard
- "Blind Spot Monitor Unavailable" message
- Mirror indicators don't illuminate when vehicles are present
- False alerts when no vehicle is present
- System works intermittently
- One side works while the other doesn't
Common Causes
Dirty or Blocked Sensors
The radar sensors require a clear path. Dirt, ice, snow, or road grime on the rear bumper can block the sensor's view. Even thick mud splash can cause temporary malfunction.
Bumper Damage
Minor bumper damage—even damage that's barely visible—can misalign or damage the sensors. A fender bender that seemed inconsequential may affect BSDS function.
Sensor Failure
The radar sensors themselves can fail electrically or mechanically. Water intrusion, electrical faults, or internal component failure disables the system.
Calibration Issues
After any bumper repair, wheel alignment changes, or suspension work, the sensors may need recalibration. Misaligned sensors give false readings or fail to detect vehicles properly.
Module Problems
The control module that processes sensor data can experience software glitches or hardware failures affecting system operation.
Wiring Issues
Damaged wiring between sensors and the control module causes communication failures. Road debris, corrosion, or collision damage can affect wiring integrity.
Diagnostic Steps
- Clean the rear bumper: Thoroughly clean the bumper area where sensors are located. Sometimes this alone resolves the issue.
- Visual inspection: Look for any bumper damage, even minor. Check for water intrusion or damage near sensor locations.
- Check for codes: Scan the BSDS module for stored diagnostic trouble codes.
- System reset: Turn the vehicle off, wait several minutes, restart. Sometimes the system needs a reset after temporary interference.
- Professional diagnosis: Radar sensor issues often require dealer-level equipment to properly diagnose.
Repair Costs
- Sensor cleaning/system reset: $0-$100
- Sensor calibration: $150-$300
- Radar sensor replacement: $300-$600 per sensor
- Module replacement: $400-$800
- Wiring repair: $150-$400
- Bumper replacement with sensors: $800-$1,500+
Living Without BSDS
If the system is malfunctioning, rely on traditional methods for lane changes:
- Properly adjust all mirrors
- Physically turn your head to check blind spots
- Signal well in advance of lane changes
- Don't become complacent—actually look before merging