[BRUCE ROE]

A dim light can be caused by voltage drop in the wiring, but a more likely cause is a bad diode. So the issue is proving the new alternator is bad, without voiding the warranty or having to fix it yourself. Swapping an alt would prove its bad. A scope on the bulb lead would show a drop in voltage on one phase (of 3) if a small trio diode is open. A higher spike on a phase means a main rectifier diode is open; without the battery load, the voltage shoots up and thru the trio to the bulb. Bruce Roe