Code Definition

B1780 — Mirror Driver Down Circuit Short To Battery

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

About B1780

B1780 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 B1780 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) 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.

B1780 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 or Driver Door Module monitors the driver side power mirror motor circuits and is able to detect short circuits between its drive outputs and battery voltage. DTC B1780 sets when the module sees voltage on the mirror down drive wire while the output is supposed to be off, or when excessive current flow is detected to a battery feed during the down command. The mirror motor is a small reversible DC motor driven through H bridge outputs, and a short to battery on the down drive line means the motor terminal is being pulled to a hot circuit through chafed insulation, a dam...

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