Code Definition

B1815 — Wiper Rear Motor Down Relay Coil Circuit Open

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

About B1815

B1815 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 B1815 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.

B1815 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 rear wiper motor down relay coil control circuit on Ford vehicles equipped with a rear wiper system. DTC B1815 is set specifically when the BCM detects an open circuit on the down relay coil drive line, meaning either the coil itself is internally open or the wiring between the BCM driver and the relay coil has lost continuity. The down relay energises the rear wiper motor to drive the blade back to its parked (down) position when the wiper switch is turned off, and the BCM verifies the integrity of the coil circuit by sensing current flow when the re...

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