This is a fine A-A set of Rock Island E8s issued in about 2000 I think and all the internal components are Lionel TMCC of that vintage. Everything works bar one thing, which is the motorized roof fans on the lead unit, which these E8s had instead of a smoke feature. The motor (which is larger than a conventional smoke unit fan motor) will spin when connected to a depleted 9 volt battery, but it seems it is not getting power from the board(s) it is connected to.
I have traced the black pair of wires all the back from the fan motor PCB (MDK-039) to another component I don't recognize, which is the white board shown below and has a number of wires connected to it and a couple of caps. I can't detect any voltage from the two black wires when power is applied to the track but it's hard to get a reading with wires so small and bunched up. Everything else seems to work however.
On the other unit, the fans spin whenever there is power to the track so I assume the circuit is connected direct to track power.
I've managed to track down a replacement MDK-039 PCB although not the white board, but wonder if there's a simpler solution, such as some TMCC off/on function. I got this set used and it did not include a manual. Any thoughts?
Incidentally, the belt and pulley system K-Line used for this feature is superior to Lionel's later gearbox on the VL Centipede, which rattles like there's no tomorrow - both are shown below: