2000 V40 Tail Light/Wiper and CEM

[gharlowe]

The red tail lights on the tailgate hatch were out on my 2000 V40 (165K miles). The dealer diagnosed the CEM (P/N 30859699).

I bought a used replacement CEM from an on-line source, which fixed the tailgate lights, but then the rear wiper stopped working. (Returning my CEM fixed the wiper again). I exchanged the new "bad" CEM for another used unit and had the exact same experience - fixed tailgate lights, wiper no longer works.

All three modules are marked with VOLVO 30859699, CENTRAL ELECTRONIC MODULE LHD 3817900-150.

Are there differences between CEMs? Any ideas?

Thanks much!