I think it will split fairly easily. No personal knowledge, a report from someone else.
To test both slow speed fans at once, just jump fused power directly to pin 1 of the thermoswitch connector. This is a definitive test of slow speed operation.
You can try to jump fused power directly to pin 3 as well, to see if the fast speed fans will work, but I have little hope that they will, due to no power being fed to the fan control module. This is not a definitive test.
If you jump fused power to pin 2 of the thermoswitch it should backfeed to the fan control module. Then put power on pin 3 and see if the fans will run in fast speed. This should be a valid test.
But if I want to know the conditions of the fans, I take the individual fan connectors apart and put power directly to the fans. Ground pin 3 of the fan connector, put fused power to pin 1 for fast speed, then take that off and put fused power to pin 2 to test slow speed.