Just came into possession of an 88 mustang GT, Need some assistance

Be
 

Troubleshooting battery drains

Typically it is something draining the battery. Small things like glove box or courtesy lights are often the culprits. If you have an aftermarket stereo or alarm system, it is also suspect.

The ideal method is to disconnect the negative terminal, and connect a Digital Multimeter (DVM) between the negative terminal on the battery and the negative cable. Set the DVM on a low current scale of 2-5 amps if it doesn't auto-range. Watch the current draw, and then start pulling out fuses. When you see a sudden drop in the current, that circuit is the likely culprit. Note that the computer, radio & clock will draw less than 1/10 amp to keep the settings alive.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf. You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

If you can’t find the current drain by pulling fuses, then the alternator is suspect or any aftermarket sound or lighting equipment that may be on the car. Disconnect the alternator output power plug, then disconnect any aftermarket sound or lighting equipment while watching the current on the DVM.
 
Let me preface this with oops!! I should have looked at page 2. I posted the below on a difference thread. My bad. I see that some of my questions have been answered above. Thanks to those that did.

This is what I posted to the other thread.

"Hello all. So, being pretty new to the fox body mustang and having been some years since I've had to get into electrical issues I'd like to get some recommendations on tools to do some troubleshooting. The car is an 88 GT convertible, 302, auto trans. My trouble spots are power mirrors (replaced the switch already), Power door locks, and 3rd brake light. Everything else seems to work as intended. All of the fuses I've checked seem to be good.

Any suggestions and assistance greatly appreciated.
Thanks"

Having said all of the above. I have a new battery, the car sat for a week while I was away. Started right up when I came back still have the issues listed above. Not sure if there is or was a battery drain or if the new battery is just that new and takes time to drain. Still looking for information on tools (which I see some above) to check for drain and troubleshoot why the items above are not working.

Thanks, sorry for the redundancy