Don't test too many things at once. Test one thing, prove it good and move on. If you undo / test several things you may introduce a feed back or fault you did not have to start with. CPS is a coil with about a 300ohm resistance. You can test in situ.
Good - Fast - Cheap: Pick any two.
E23 735i; E30 318i; E32 735iL (X 2 - 1 Alpine White and 1 Glacier Blue); E34 535i; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i