Code Definition

B1640 — Mirror Passenger Left Circuit Open

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1640

B1640 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1640 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1640 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Body Control Module (BCM) or door control module monitors the output driver circuit that controls the left side outside mirror motor, which is the passenger side mirror on right hand drive vehicles. DTC B1640 is set when the module commands the mirror to move and detects an open circuit on the driver output, meaning current is not flowing through the motor windings as expected. The mirror motor uses bidirectional voltage applied through paired output drivers to position the mirror glass for vertical and horizontal adjustment, so an open circuit on either output line will prevent at least o...

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