Manual Transmission

WARNING: This page is about a different car, the 2013 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

The PCM sends a voltage signal to the reversing lamps switch. When the transmission is in REVERSE (R), the voltage signal is routed back to the PCM and the PCM sends a message to the BCM-B indicating the transmission is in reverse.

DTC B1277:15 (Reverse Lamp: Circuit Short To Battery or Open) - sets when the BCM-B detects a short to voltage from one of the reversing lamp output circuits.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Reversing lamp switch (manual transmission)
BCM-B
PCM