Code Definition

B1790 — Autolamp Sensor Input Circuit Failure

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

About B1790

B1790 is a manufacturer-specific body diagnostic trouble code recorded for Ford vehicles. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1790 is stored, the module has detected a sensor-related fault — the reported value from the named sensor is out of spec.

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.

B1790 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 autolamp sensor circuit to automatically control the exterior lighting based on ambient light levels. The autolamp sensor, typically a photocell mounted on top of the dashboard under a translucent dome, generates a variable voltage signal proportional to the ambient light intensity. DTC B1790 sets when the BCM detects that the autolamp sensor input voltage is outside of the expected operating range, indicating an open circuit, short to ground, or short to power within the sensor circuit. When this code is set, the autolamp feature will not function co...

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