Engine fan control output

[Hamish]

My CM870 only delivers 8 or 9 volts to the engine fan solenoid. I think this is the cause of very lethargic fan turn off (and on), which will wear out the hub quickly as it slips during the transition.

I have checked the relays (2007 International 9900) and they are fine. Is this a failed output driver in the ECM?

I could just wire it old school using a coolant temp switch and the AC high pressure switch, but do I have a bigger problem with the ECM?
Are there any other issues that will develop because the ECM may be failing? Does this warrant an ECM swap? Can this even be done without programming if the part number, cpl, and program version are identical? (I could swap one from another truck I own or just buy a used one if I find one)

ps. Searching the forum didn't seem to be working - i was pretty sure I saw relevant posts about this in the past...