The BR-373 TGV in the OpenPak128 nightlies r1039 and r1040 has a constraint bug which makes the vehicle unplayable (I'm sorry it was my fault -typo-).
Download this file and overwrite the existing one in the pak folder to fix it. It will be of course fixed in next nightly release. I'm sorry for the inconvenience.
Edit: It should be fixed since r1041. Please, download last nightly to fix this problem.