When I turn headlights on car goes dead

Hello my name is Dave,

The first thing we should do is confirm that the alternator is charging, even though you have replaced it there is the possibility that the new one is faulty or there is another previously unknown issue. Here is a link to our tutorial on testing your alternator:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

If the alternator test finds it to be functioning properly then I would suspect a connection issue, since your car has a side post battery the battery terminals are a good place to start, make sure they are tight but be careful as they are very easy to strip. If you find that the terminals are tight the next thing I would check would be the battery ground cable to the engine. An easy way to test this is to use a set of jumper cables and attach one black clamp securely to the engine and the other black clamp to the negative terminal of the battery, start the car and see if the problem persists, make sure to double check the clamps as you are checking it, especially the one on the battery. If this makes the lights remain bright then replacing the negative cable will solve your problem.

another connection to check and make sure is good is the body ground, usually a flat cable that goes from the engine to the firewall. If none of these prove to be your issue please get back to us and let us know.

Please keep us up to date on your progress and thank you for using 2CarPros!