Code Definition

B1818 — Wiper Rear Motor Up Relay Coil Circuit Failure

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

About B1818

B1818 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 B1818 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

B1818 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 up relay coil control circuit on Ford vehicles equipped with a rear wiper system. DTC B1818 is set when the BCM detects an electrical fault on the up relay coil drive line, typically an open circuit, short to ground, or short to battery voltage. The up relay is the device that energises the rear wiper motor in the up direction (driving the blade across the glass during a wipe cycle), while a separate down relay handles the return to the parked position. The BCM commands the relay coil by pulling the control line to ground while monito...

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