Hi,
The sunload sensor is on the dash right in front of the driver and is a photodiode. See pic 1 below. The purpose is this. This sensor converts the sunload amount to a voltage signal and signals the AC auto amp of conditions.
I attached the diagnostics for the B278D below. Additionally, I included the diagnostics for the sunload sensor as well. With the sensor, chances are the sensor itself has failed, but the diagnostics will prove it one way or another.
Let me know if this helps or if you have other questions. Also, you will be working around high voltage so it's important to be careful.
Take care,
Joe
See pics below. The last pic shows the location of the sunload sensor.
Images (Click to make bigger)
Monday, April 25th, 2022 AT 8:09 PM