Would say, if thermostat housing reads close to 160, then you might be ok. If housing is also hot, then look at the circulating water pump on the front of the motor
Need to scan the motor for codes
My thought is there is a sensor wire which is disconnected
Gray to B-21 (Ground)
Dark Blue/White to B-11 (Sense)
Black/Pink to B-1 (5V)
Recon I got nothing else to offer, wish I did. An ALT is a pretty simple device, apply 12V to S and Ex, rotate and so long as they are connected to the Bat being charged they work or they don't