Mustanguru

My battery completely drains, cannot be charged, if I leave the cables connected once the car has been turned off. It's an 88' RX-7 - any help is appreciated.

RX-7 GT

not trying to say your dumb or anything ....but have you had a good look see at the cables, terminals? sometimes they can be corroded and are miss took for a drained battery.

Mustanguru

Yes, unfortunately I have done that. I have replaced the battery also thinking maybe it was just bad. I'm thinking it may be electrical because my alarm system went bad and since then I've had problems. The headlights are also stuck on up because they quit working, along with the antenna. In fact, the antenna motor just ran and ran for the longest time. Any other suggestions? I appreciate the feed back.

I really don't know a thing about doing work on foreign vehicles.

Icemark

Foreign should not make any difference, a battery drain problem on a mustang is the same as for a RX7. Hell, Ford even used the T2 tranny as well as a lot of other Mazda parts on a lot of Mustangs. So get it out of your head that it is a foreign thing.

If you have a current draw you will need to determin what to draw is coming from. To do this on any car or truck, the simplest way is to get yourself a digital Multi-meter. They can be as cheap as $35 at Radio shack or as expensive as a couple of hundred, But for this test it just needs to have a Amperage scale on the meter, and be capable of testing up to 10 amps. They should come with instruction on how to test, but in case they don't or you lost them:

Disconnect the positive battery terminal, close the doors, turn off the dome light.

Insert the meter (set for amperage) between the pos battery post and the pos battery cable. Pos lead of the meter on the Pos battery terminal, neg lead of the meter on the Positive battery cable that was formerly hooked up to the positive battery terminal. If you have an aftermarket alarm, it will go off at this point. You will want to disarm it.

The meter should read between 50 to 60 MA (mili-amps) or .05-.06 or so, up to about .075 MA. If it reads more, like .110 or .150 you have a relay active. If it reads a lot more like 1.2 or 3.5 you have light bulbs or stereo amps stuck on in the car. Less than .075 and there is no problem, other than a bad battery, bad alternator, or bad battery and/or alternator connections

So if you have a draw larger than .075; its time to do some disconecting.

Start pulling fuses One at a time! . It doesn't do any good to pull more than one at a time, because you are trying to find what circuit the draw is on. When you pull the fuse and the meter drops back down to .075 or lower you located the circuit.

Now you will need a copy of the schematic to see what is on that circuit, and find out if it is a bulb that is on or a relay thats stuck or what. For the RX7 there are a couple of sites that have the shop manual posted, in case you haven't spent the $15 on a Chiltons yet. Test each thing on that circuit to see if it is working correctly, in worst case unplug each thing at its connector to determine where the problem is. You can always pretend you are a Mazda dealer Mechanic and just replace without testing everything on the circuit too and hope that fixes the problem.

Again this works for all cars and trucks, not just Mazdas and is something an electrical shop can do for you but will generally charge you $50 to $200 to do.