Does it run any different? Poor fuel mileage? As Tanker said check the vacuum lines. Your boost gauge is fed by the vacuum lines so if you have one that's broke or leaking it won't register boost in the DIC. Also check the BCS as he said too.
My old 99 would only make ~half boost on the DIC. I swapped BBV, messed with vacuum lines etc until a member here said to check the BCS. What you can do to check that is simply disconnect the vacuum line from it. Solved my half boost, irratic shifting, irratic T/C lockup, as well as terrible fuel economy.
