1984 Mercury Grand Marquis mileage: 150,000. Refresh my memory a bit; I forgot how to check if my alternator itself is okay. Alternator currently in vehicle was rebuilt and boosted to 100 amps instead of the normal 65-70-amp type. Your response would be greatly appreciated. Thank you.
Assuming the battery in your car is in good condition, you can check the alternator by having the engine on a fast idle with the headlights and the air conditioner on. The voltage across the battery should be 14 to 14 volts. Double check to see that the alternator belt is tensioned properly and in good condition.