1999 Yamaha G16-ET "ULTIMA" (36V - DC MOTOR) Service and ...
G16ET is the code for the 1999 ULTIMA running the 36-volt DC motor, and LIT-19616-G1-60 is the part number of the manual Yamaha wrote for it.
Because the G16 stayed in the range from 1996 to 2002, that one volume covers all seven years and thirteen sister models, the electric G16-EP, G16-ER, G16-ES, G16-EU, G16-EW and G16-EX together with the carburetted G16-AP, G16-AR, G16-AS, G16-AT, G16-AU, G16-AW and G16-AX.
What a dealer got from this book is what you get: factory maintenance intervals, motor and controller procedures with the readings to expect, charging system checks, complete wiring diagrams, and chassis and brake work quoted with Yamaha's own torque values and service limits. The troubleshooting chapters start from the symptom.
Fitment is confirmed by the plate, which should read G16ET.