Unknown voltage draw HELP!!!

[shrtchev]

Alright guys here is what i got. My 04 tahoe had a dead batt one morning. Thought oh no big deal wife must have left int light on. Charged bat back up drove car for the rest of the day thought nothing of it. problem solved. Wrong next morning same thing dead as a door knob. So i start thinking well maybe bad batt (dead cell or something) R2 batt and once again truck runs great. 2 days later same prob dead as a door knob. So now im pissed. I start troubleshooting more. I have removed starter and alternater and still pulling juice( verified with multimeter) Where i am now is it is coming from main fuse box under hood. Pulled every fuse out individually and still have current draw. I am out of ideas/avenues. Please help has anyone heard of this? My next plan of attack is to find something headed towards fuel pump as i read on here that could be cause of problem. Thanks in advance for any advice!!

 

[Sepiroth]

I remember a GM tech telling me that there was a TSB on the Trailblazers. It was in response to dead battery on Dealer stock.

Evidently these thing had to be started once every 3 days to prevent all the modules in these things from killing the battery.

Have you had the battery tested? By that I mean, taking the battery someplace and having them do a test to confirm how good the battery is.

Same as the charging system, do you know it is good.

Check also your glove box light, if applicable as well as an underhood light.

 

[oneradride]

Remove the negative battery cable and hook a test light inline where the cable was.
To be more clear – after the cable is off. Use the clamp of the test light on the negative post and the prod on the cable. Essentially bridging the gap from the removed cable….
With the doors closed, hood light removed (or off) ignition off, basically everything in a state of rest, the light should be off.
If you have any kind of current draw the light will be on. The brightness of the light will vary depending on the draw.
Now, if it’s on, you can start pulling fuses until it goes off. This will help you determine what circuit, if any, is at fault.

 

[mikeb33]

The drain you describe is called "parasitic draw". When you first disconnect the battery, and then reconnect it, all the modules re energize and this can take a while. The test light or meter reading is not a legitimate test right away.
There is a tool that goes between the battery and cable and you connect your meter to it. You turn a knob and the circuit is disconnected, now with only your meter allowing voltage to pass. You can take a good reading since the power to the car was never interrupted. I found a good write up on draws: http://flashoffroad.com/electrical/Batteries/BatteryDrain.html

I had a van do this a few years ago and it started everyday, but if i left something on for even a short while, the battery died. The dealer(it was under warranty) tested it a few times and said it was fine. They even put a starter on, but if I ever left the radio or lights or anything on for even 20 minutes, dead. I went back and they tested the battery and sad fine. I turn the high beams on for 10 minutes and had them test again: FAILED. I finally got my free warranty battery.

 

[shrtchev]

Ok i have done the test above and the light remains on but i did notice something weird when i was driving it. After i was done the battery symbol on console and indicater PRND321 stayed lit. I stayed in truck for 10 minutes. Do you think it could be coming from my dash?????

 

[mikeb33]

So how many amps is the draw?

 

[shrtchev]

figured it out it was coming from my auto start system. I disco'd the box and the light went out. Thanks for all the help must be a short internally.