I contacted the mfr with a few questions about the fan fail module operation. Here is his reply:
"The DeLorean fan fail unit was very simple, it had counter wound coils in the 2 fan supply line which were wound round a reed switch. The current through each coil created a magnetic field, if both fans are running the fields cancel each other out and the reed switch stays open.
If either fan failed, the field of the running fan will cause the reed switch to close signalling a failed fan."
I asked more questions about its operation with lower current load fans and here is his reply:
"If you've swapped to lower current draw fans then that is fine, better in fact. As long as the fans are both the same then the fields will cancel each other and the principal of the unit remains the same.
The unit was originally designed with a lower current fan, but then during the vehicle development DeLorean had cooling issues (it was always marginal on cooling) and swapped to much bigger fans without telling us, that's why the units fail, the fans take much more current than the unit was original designed for.
The resistors are I believe in line with the signal telltale so yes, any resistor of the same value will do.
Often it's the reed switch that goes, it's quite a sensitive reed, 12 to 15 ampere turns I believe."
Reproduced with permission.
Nick