One of my friends is ready to buy a 92 400SE,W140,power seat,keyless entry and back-up sensors dont work.Owner said that the "convenience pckg. module "needs replacement,is this a resonable diagnostic?

The pnuematic system pump (PSE computer) has 5-6 different "jobs". Including door locks, back-up assist, headrest fold-down, ortho-seats, retractable trunk handle, & manifold vacuum assist.
Operation of power seats is done by a computer under EACH front seat!

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