January 23, 2016: Since the service manual was telling me that my error code meant the X-axis end of travel sensor was incorrectly being triggered, I found the sensor labeled "end of travel" and bypassed its wiring harness. I used a brand new sensor. I started a print that always causes the fault code, and unfortunately, it faulted again. Bypassing the sensor wiring didn't fix it!
I opened the printer and started it and I manually triggered the sensor that was labeled end of travel. A completely different error code showed up on the LCD! I triggered a neighboring sensor that is labeled as the X-axis home sensor, and the correct error code showed up. Since the service manual didn't match the sensor labels, I bypassed the wrong sensor!
I bypassed the correct sensor now and I'm currently running a test print. Fingers crossed.