This code typically appears when the security system's central control module cannot talk to the alarm siren. : Battery Backed Up Siren (BBUS). Failure Type : Signal missing or message failure (-87). Typical Symptoms : The alarm may not sound when triggered. "Alarm System Fault" message on the dashboard.
: The siren is often located in an area prone to moisture (e.g., behind the wheel arch liner or near the bulkhead). Inspect the connector for green corrosion on the pins.
If no wiring or battery fault is found, – internal PCB failure is the most common root cause for B1D1787 in 2013–2020 Land Rovers.
: Ensure the connector to the siren is clean and secure. Corroded pins are a known issue in the wheel arch area where sirens are often located. Replacement :
If power and grounds are good, and software updates do not clear the code, the amplifier is confirmed dead.
