i was just wondering what that windows is on my ecu, actually havent seen mine but i pulled one out a 89 hatch manual at the junkyard cause my car has problems no one can explain..

is there a light in there that lights if theres a problem or somthin?

 

It's a sight glass.
if you get a code.
you pull up passenger side carpet and check that red led on ecu.
Count flashes and take it from there

 

2nd time posting this in 10 min...