Have you tried removing the harness plug and throwing 12v across the blades on it to see if it does it's thing? (polarity is not an issue, just 12v + on one and - to the other)
If that works you issue lies with the connection on the TPS or the TPS setting, the fuse near the radiator overflow bottle, the TPS proper, the wiring, or at the extreme, the circut board inside the solinoid plug on the harness.