RE: CEM/REM on V70
If they are indeed bad then no there is no cheaper way.
But I would check all the battery terminal connections and connections to the REM. Then REM(fuse panel) is mounted under the panel by the L/R taillight.
The CEM is under the dash on the L/S of the car. You will see a bunch of relays in it.
I have seen bad connections cause this problem quite a few times. It is usually at the battery and cables.
1987 Ford mustang LX Coupe 5.0
1995 Yellow T5-RM running
1996 850 turbo
1994 N/A 5-speed wagon Purple (daughters)