If I understand the schematics correctly, that pretty clearly points to the 1a fuse?
I agree. The problem is definitely within the Switch and Fuse module. Since the fuse is the weak link, that is most likely the problem.
As an educational experiment, connect the test light between ground and the yellow "C" wire. The test light will load the circuit. Now measure the voltage coming from the Switch and Fuse module. Notice that the voltage is no longer 9.7, but has dropped to zero. More meaningful voltage test results are obtained when circuits are under load.