Bosch

Sent by the fuel injection ECU
The shift indicator lamp is controlled by the fuel injection ECU on vehicles equipped with manual transmissions only.
The lamp (upshift arrow) is located in the instrument panel. It assists the driver by indicating the "general need" to shift into the next higher gear. This will improve fuel economy and reduce the dangers of operating the vehicle in the wrong gear.
The fuel injection ECU sends a current to the lamp when upshifting is to be indicated.