Refresh my memory a bit; forgot how to check if my alternator itself is ok.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.

what are yo utalking aobut

your battery would go dead if anything was wrong.

If u have a voltage meter, u can probe the three wires coming off the alternator. Ford/Merc should have a yellow wire with black stripe. This is the positive lead for the regulator. Start ur car, check voltage, then turn on headlamps or press brakes. It should be around 13.6 to 14.4 before the regulator, if voltage drops more than 3 volts u may have a alternator on its way out.

You can also start the car, & disconect the positive batter cable while the car is running. If ur car can not maintain the proper voltage to keep it running ur car will die when u step on the brake or turn on the lights.

If the battery in your car is in good condition, you can check the alternator by having the engine on. The voltage across the battery terminals should be 13.5 to 14.5 volts. Double check to see that the alternator belt is tensioned properly and in good condition.

99 Grand Marquis is alternator is usually around 135 amps