Hi,
I attached the wiring schematic for a 3500 below. The 4500 should be similar. If you have power to that alternator, the next thing is the ECM.
The ECM is responsible for the duty cycle of the alternator. The duty cycle of a vehicle's alternator reflects the percentage of time it operates at various levels of electrical output, since we know the alternator is good and it has power, this is the next suspect.
In this case, I would recommend using a live data scan tool to check the duty cycle and for diagnostic trouble codes.
I attached the schematics below. Note that these were made with one or two alternators, so you will notice both in the schematic.
Take care,
Joe
See pics below.
Images (Click to make bigger)
Thursday, September 21st, 2023 AT 5:44 PM