Code Definition

B1789 — Mirror Passenger Down Circuit Short To Ground

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

About B1789

B1789 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 B1789 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.

B1789 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 passenger side power mirror motor circuits and is able to detect short circuits between its drive outputs and chassis ground. DTC B1789 sets when the module commands the passenger mirror down output but detects that the drive line is being pulled to ground externally, resulting in excessive current flow or loss of expected output voltage. The mirror motor is a small reversible DC motor driven through H bridge outputs, and a short to ground on the down drive line means the motor terminal is being clamped to ground through chafed wiring,...

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