Transmission fluid flow (applies to all XJs and XJSs)

Hello 

The transmission oil pump, located above the filter in the reservoir, forces fluid into the transmission selection mechanism and transmission itself.

On one side of the motor/transmission there is a large hose that goes to the transmission cooler co-located with the engine radiator. 

The automatic transmission fluid (ATF) going to the cooler is still under pressure after having done its job in the selection mechanism and transmission itself. 

No problem. 

Transmission fluid, which has been heated, gets cooled before returning. 

What I am used to is the now-cooled ATF returning immediately to the transmission reservoir. However the return from the cooler also goes to another large hose on the other side of the motor/transmission. 

My question is: Does the ATF perform additional work before returning to the reservoir. or are there other mechanisms still being lubricated? 

I ask this because I’d like to purge the standing ATF in the cooler and lines after replacing the fluid and filter in the transmission pan (reservoir). 

To do this I'd like to replace the filter and AFT in the reservoir, then disconnect the return hose at the cooler and (periodically topping the up the reservoir) run the engine until the old (discoursed) AFT is flushed from the system.

I want to be certain I will not run any mechanism dry.

My owner’s manual (genuine Jag) is not clear on this.

Thank you very much. 

Regards 

Richard