parasitic drain got me stumped

[Dario]

Go under the hood in the fuse box and find ur starter relay and the a.c. compressor relay and swap them around with the vehicle not running. I had this proble and what it was was the a.c. compressor relay was stuck closed circuit making it drain over night. U can check it by swapping it w the starter relay and if u put the compressor relay I'm the starter spot and it tries to crank then u know u need a new compressor relay and problem solved. It had me baffled until I found on Google one guy that had the.same issue. Easy to test and cheap fix so might as well try it

 

[Sean James]

After attaching an ammeter, multimeter, dvom, etc. You must let the modules "go to sleep". Leave the wires on the meter and go away for an hour or so. Come back and get your reading. I know this doesn't apply to op's problem, but just wanted to throw this in here so you'all don't spend 2 hours pulling fuses and pulling on wires like I did. For us old school guys that are new to computerized rigs.

 

[Tahoe97]

Same problem here on my 97. I just went through 3 batteries in 4-5 months installed by the dealer only to finally have the dealer discover it was the passenger side vanity mirror that was drawing the current. I had already cut the power to the driver's vanity mirror and the dealer cut the power to the passenger vanity mirror. So far so good. Years ago I also discovered that the plastic switch that activates the light in the glove compartment cracked and broke away from the housing, automatically turning the light on without opening the glove compartment, and burning out my battery without me seeing any light or open glove compartment. So I removed that switch and capped off the hot wire. Make sure that is not the reason. Good luck.