Adding a manual fan switch??

[JMBT]

I did a little more digging about doing this mod on a Volvo with a cummins motor. Here is what I found in the VECU and BBM manual on Volvo's website, in reference to connecting a 12V+, switched lead to the PA19 terminal.

"When used for a Volvo engine, the manual fan input must be connected as shown above. When used with a Cummins engine, there are two choices:

• Wire to the VECU as outlined above. However, the multiplexing setup in the ECM must be such that the “fan accessory switch” is enabled. The general “fan fea- tures” setup should be disabled.

• Wire to the ECM. In this case the manual fan must be enabled in the general “fan features” setup, and the wiring to the ECM must use a Normally Closed (N.C.) switch to ground instead of the N.O. switch to +V shown above for the VECU connector."

I can change the multiplexing setup of my ECM with Insite, to enable a fan switch through J1939, but when I do this I have to pick an address "source" that the command will come from, from a drop down menu. There are about 200 choices, none say VECU. So I am trying to figure that out next....
My other options are wire into pin #25 on the OEM, ECM harness, or add the second soleniod like Rawze mentioned above...