Code Definition

B1588 — Autolamp Delay Increase Circuit Open

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

About B1588

B1588 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 B1588 is stored, the module has detected an open (broken or disconnected) electrical path 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.

B1588 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 increase circuit, which carries a variable signal from the headlamp switch potentiometer used to set how long the headlamps remain on after key off. DTC B1588 sets when the BCM detects an open circuit on the autolamp delay increase signal wire, meaning the expected continuity from the switch through the resistor element back to the BCM is missing. Common causes include a broken wire, disconnected switch, or a failed potentiometer wiper. With this code present the a...

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