I think I know what's going on here.
On the 767, probe heat is "not" crew controlled. Pitot heat comes on low with engine revolutions. All other probe heat.... AOA, Total Temp, and Static Ports also come on with signals from the engine speed cards. Pitot heat comes on high when the aircraft breaks ground.
On the 737 with this modification, they're using engine oil pressure to control probe heat. If the engine has oil pressure..... it's running. The aircraft will turn on probe heat when it senses a running engine. (I didn't verify this via the prints, but I would guess I'm correct.)