I am hopefully going to be buying a 87' z28 in the next week. It has a short that is causing the battery to go dead. Any ideas on what it could be? How do I go about testing to find where the short is?

 

If you had a short, the car would be on fire.
You probably mean a drain.

You can start pulling fuses one by one to see which one eliminates the drain. It helps to hook up a meter between the battery positive terminal and the positive cable and set it to DC current. That way you can see instant results after you pull each fuse, no need to wait overnight to see whether the battery drained.

The most common drain sources are radios, amplifiers, CD changers, GPS units, trunk lights etc.

Hope this helps.
Lou

 

I'd say aftermarket alarms are especially troublesome.

 

Ok, well I should be able to pick up the Camaro soon. It is a 86 z28, not a 87. It does have a aftermarket radio installed in it, but that is all I can tell as far as electronic mods go. I guess I will have to wait till I get the car in my name before I check it out good.

 

Watch out for the bad alternator too... It could drain the car completely overnight, especially if wired incorrectly. So if you check all the fuses and everything looks good, look at the alternator.

 

Another draw that comes to mind: trunk light. It can stay on if the trunk latch switch is broken etc.

Let us know what you find.
Lou

 

Also just an idea but you may want to check the positive battery cable going to the terminal block.. Also the Terminal block itself may be corroded and causing the positive system to ground out on the frame.. Mine had the same issue but mine is an 82 Z28. I fixed the problem by breaking apart the loom and checking all the positive wires and grounds. I had to do this because I got no result from the fuse test. There is a test light trick that they dont reccommend but it worked for me.... You should also check the ground straps... Hope this helps....

 

How quickly does the battery drain? If it takes 2-3 days - see if the fuel pump is running constantly. Can test by opening trunk and putting your ear on the hump, when it's very quiet outside (like late at night).

I know it sounds weird, but...

The fuel pump gets power directly from the battery through the Oil Pressure Sending Unit (OPSU). Regardless of keys, running, off, on, or anything else, a bad OPSU can make the fuel pump run constantly - my 1992 did this and it drove me crazy for 2 weeks until I heard it running late one night, and the keys were in the house!

 

Thanks for all the suggestions guys. I am hoping I get the car by the end of this week. I am dying to get it, lol. I took the battery home and charged it up and then took it to Kragens the next day to get it tested and its perfect. The alternator was just replaced, so its not that. I am thinking its gonna be a simple fix since I have a feeling the owners husband doesn't know too much about working on cars. The good thing is it has a rebuilt engine with low miles, brand new tires with 5 miles on them, brand new interior, and a bunch of other brand new parts.
Here she is. Can't wait to clean her up!

Its a nice move from my 96 Dakota V6!