In message , Franc Zabkar
writes
If the device is a fuse (unlikely), then one end would probably be
connected to the supply pin (or to ground).
Which could be equally true of a thermistor. AFAIK though, the
thermistor on the fans used by Dell are just there for the fan's
internal electronics so replacing with a 'standard' fan would be an
acceptable way to test as the system doesn't use it to measure
temperature.

You could also bypass the device with a low resistance, say 100 ohms,
if only for testing purposes.

FWIW, here is a pic from the service manual:
http://www.users.on.net/~fzabkar/sffprcs5.jpg

- Franc Zabkar

--
Clint Sharp