Code Definition

B1687 — Lamp Dome Input Circuit Short To Battery

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

About B1687

B1687 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 B1687 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.

B1687 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 Generic Electronic Module (GEM) monitors the dome lamp input circuit, which carries the signal from the manual dome lamp switch and the door jamb switches that command the interior dome lamp. DTC B1687 is set when the BCM detects that the dome lamp input circuit is shorted to battery voltage, meaning the input pin is reading high regardless of switch position. A short to battery in this circuit is typically caused by chafed wiring contacting a battery feed conductor, a failed switch shorted internally, or a connector that has water or debris bridging the input ...

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