[Silly Little Cars] Cushman electronics and cooling

[Peter Washburn]

Does anyone know the details of the cooling cycle in the Cushman haulster (Model 898487 to be specific)? 

The challenge I am having is that the voltage drops to ~10v and the alternator struggles to keep up while the radiator fan is engaged. 

The voltage drop does not specifically occur when the fan is going, but rather in the middle of the cycle (while the fan is on). 

What I'm wondering is if there is some other circuit that is meant to be turned on at some point in the cooling cycle? 

I have the parts manual but it is light on detail.

Thanks,

Peter Washburn