The ztweakedoom4_secondpack.pk4 file you have requested: Modifications / Single Player / W to Z Titles / Doom 3 Tweakedoom 4.0 Single-Player Mod (Patch) - 673.43kb is not available. Perhaps try browsing all files for the game Doom III and upload any files you want to share or are missing. This is the only information we could locate:
Just put this file instead of the original one to use the vulcan. This is the patch for the Tweakedoom4 Second Pack. It corrects a bug that makes the vulcan not to work.