1991 gmc sierra 2500 diesel dash lights?

[little one]

okay, more simply this time

i need to know what icon is located in the center directly above the fuel gauge

a previous owner took great lengths to cover this light with either a piece of electrical tape or a piece of black plastic (behind the plastic cover/bezel)

it is not the glow plug, service filters, or check gauges lamp

the only reason i can tell there IS a light is it's reflection is visible after dark on the upper inside dash

it is an amber light

are there any 91 gmc sierra 2500 diesel owners out there who can just tell me what the light is?

[tronary]

I would guess it is the high beam headlite indicator. They can be quite annoying when driving at night