Code Definition

B1797 — Lamp Headlamp Low-Beam Circuit Short To Ground

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

About B1797

B1797 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 B1797 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit; and a signal or supply voltage lower than the expected operating range.

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.

B1797 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) monitors the low beam headlamp circuit by checking current draw and the voltage state on the controlled side of the headlamp driver. DTC B1797 sets when the BCM detects that the low beam output line is being pulled to ground at a time when the lamp circuit should be at battery voltage or floating, indicating that the wiring or load has shorted to chassis ground somewhere between the BCM driver and the lamp supply path. To protect itself, the BCM typically disables the output once the short is detected, since sustained current through a grounded driver will damage ...

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