Everything is slow in DIS, a lot of waiting around!
Here's a manual for DIS:
https://www.dropbox.com/s/yw0kitweakag1l9/GT1-DIS-Manual.pdf
More info:
https://www.dropbox.com/s/muajavvz83tkrbg/GT-1%20Components%20and%20Functions.pdf
Another guide:
https://www.dropbox.com/s/y8ldbt254aarmh3/DIS%20Diagnosis%20Guide.pdf