What does it mean?
B1841 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Sunroof Open Switch Input Circuit High .
Symptoms
- Sunroof does not respond to the open command at all
- Close still works while open is dead, or the reverse on some layouts
- No motor sound and no movement when the switch is pressed
- One-touch and tilt functions no longer available
- Fault stored every time the open button is pressed
Likely causes
- Open circuit in the switch signal wire between the console and the module
- Switch contacts worn so they no longer close when the button is pressed
- Overhead console connector unplugged, loose or with a backed-out terminal
- Missing or high-resistance ground for the switch
- Signal wire shorted to battery voltage after an accessory or roof console installation
- Corrosion inside the connector after water has run into the headliner
- Module input holding the line high
How to fix it
- Watch the switch status in live data while pressing the open button
- Unplug the switch and test the contacts for continuity when pressed
- Verify the switch ground with a voltage drop test
- Continuity test the signal wire from the console connector to the module
- With the module unplugged, check whether battery voltage is present on the signal wire
- Dry and clean the console connector and renew corroded terminals
- Replace the switch or repair the harness, then reinitialise the sunroof travel