Code Definition

B1593 — Autolamp Delay Decrease Circuit Short To Battery

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

About B1593

B1593 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 B1593 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.

B1593 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) on Ford, Lincoln, and Mercury vehicles equipped with the Autolamp system monitors the autolamp delay decrease signal wire from the headlamp switch potentiometer, which is used to shorten the headlamp delay time after key off. DTC B1593 sets when the BCM detects that the autolamp delay decrease circuit is shorted to battery voltage, meaning the input is being pulled high outside its normal operating range. This typically results from a chafed signal wire contacting a B+ feed in the same harness bundle, an internal switch failure, or moisture bridging at the headlam...

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