1994 Holden Commodore the car does not want to change gear

My car doesnt want to change its gear. The alternator is damage. Each time when I repair the alternator, it will run normaly and the gears will work properly, but only for a few kilometers, suddenly the gear doesnt want to change again. When I turn off the car, and I start the engine again, the indicator engine light will not turn off. And the alternator is broken again.