"wast odor control" and Drain pipes

[John Mann]

I am replacing the drain pipes under the coach because the waste odor
control motor broke at the fitting and someone previous to me had
replaced the pipes, but put the valves in the wrong order at the black
water. Looking at my blue book diagrams it doesn't show the odor
control motor in the schematic. Presently the two are tied into the
system after the valves or down from them. Is this correct? Where in
line should they be A. tank/motor/valve or B. tank/valve/motor as they
are now, seems that it should be A. not the way it is now. I
appreciate anyones input? Thanks.

John Mann
1985 pt40
Granbury Tx.