B1783: Mirror Passenger Up Circuit Open
What does B1783 mean?
B1783 is a diagnostic trouble code indicating "Mirror Passenger Up Circuit Open". This means there is an electrical break in the doors & windows wiring — a connector may be unplugged, a wire broken, or a component has failed internally. The ECU detected no signal where it expected one.
Symptoms you may notice
- Check engine light (MIL) illuminated on dashboard
- Intermittent warning lights
- Erratic gauge readings
Estimated repair cost
Typical range in Australia (parts + labour)
Common causes
- Damaged or corroded wiring harness
- Loose or disconnected electrical connector
- Failed doors & windows sensor or actuator
- Blown fuse in the related circuit
- Poor ground connection
What should you do?
This code sits in the body control module or something wired through it. That module runs the unglamorous things you only miss when they stop: headlights, wipers, indicators, central locking. The car will usually drive, but check what has actually stopped working before you rely on it at night or in the wet.
Get a diagnosis for YOUR car
Code B1783 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.