Power drain- Tahoe 2003

**BIGREDDADDY53** · 02-21-2013, 06:51 PM

Hi - I have a power drain when the truck is on or off. I can watch the volt gage and see it drop to under 12volts. I was wondering if it might be the coils or something like that. Does anyone have some ideas on this........Thanks, Eric

**Conlan Rose** · 02-21-2013, 07:17 PM

Best way to test is start truck and carefully turn each accessory on and off and see its affect of the voltmeter. Also test the voltage at the battery while running it should be about 14.4. Does it happen with any other weird thing going on with the truck? How old is the alt, battery, and are you using factory cables and what electrical mods do you have. Also just run the truck with 0 accessories on and see if it happens just sitting no driving, maybe reving a bit.

**RayVoy** · 02-21-2013, 07:29 PM

Eric, follow @Conlan Rose 's advice and you should find the problem. If your dash gauge is reading correctly, that is a large drain, I would suspect the alternator, or the battery.

**BIGREDDADDY53** · 02-22-2013, 01:44 AM

I did all that and then I took it to my mechanic he hooked up this charging unit and I shut the truck down took the keys out and he said there was still a power drain. HE said it was a short. The battery is new and he sold it to me in Dec. (was supposed to be around 800CA but this one was650CA) cost me about $150 and I still have to get the right one latter, and I will keep this one for my second one. Anyway He said to drop of the truck and he would try to chase down the short but could take longer than a day. I don't completely trust him so if anyone might have any ideas. Thanks Eric

**RayVoy** · 02-22-2013, 07:17 PM

Any load that is draining the battery that fast should not be hard to located. Try pulling fuses while the meter is monitoring the battery (I would monitor current, but you may be more comfortable monitoring the voltage). You don't need the key "on" if it's draining all of the time.

**BIGREDDADDY53** · 02-24-2013, 02:04 PM

Originally Posted by RayVoy

Any load that is draining the battery that fast should not be hard to located. Try pulling fuses while the meter is monitoring the battery (I would monitor current, but you may be more comfortable monitoring the voltage). You don't need the key "on" if it's draining all of the time.

I did this and no luck. I pulled all fuses one at at a time and the volt metter stayed at 12 volts.Thanks Eric

**RayVoy** · 02-24-2013, 03:49 PM

Originally Posted by BIGREDDADDY53

I did this and no luck. I pulled all fuses one at at a time and the volt metter stayed at 12 volts.Thanks Eric

OK, so you need to watch the current drain.
Get a meter that will read 5 to 10 amps, set it in series with the pos battery cable and do the one at a time fuse pulls again.

**j cat** · 02-24-2013, 04:37 PM

Originally Posted by BIGREDDADDY53

I did this and no luck. I pulled all fuses one at at a time and the volt metter stayed at 12 volts.Thanks Eric

sure it can be a device like a small light bulb in the glove box or other lighted compartment.

even a wire with a worn covering draining the battery.

most times on a vehicle this old the alternator will suck down the battery on shut down. this is when the charging diodes internal to the alternator start to fail. I would remove the red alternator wire then check for leakage with a DC amp meter.

disconnect the battery ground before removal of the alternator wire. tape the lug for safety then connect the battery ground connection and see if you have a drain thew the alternator red wire. this should have no drain if good. remove alternator to have it tested. AZ can do this at most stores. If it is bad get new not rebuilt. rebuilt does not last.

- - - Updated - - -

Originally Posted by BIGREDDADDY53

I did this and no luck. I pulled all fuses one at at a time and the volt metter stayed at 12 volts.Thanks Eric

the procedure to check for a leakage is to measure the load current when the engine is OFF using an amp meter. current should be less than 200ma. you must wait about 15 min because of security system shutdown to settle down.

amp meter is in series with the load , NOT ACROSS ! best place to do this is "between" the battery connection at the battery post and the ground battery connector.

YOU WILL NEVER FIND LEAKAGE WITH A VOLTMETER !

**Pikey** · 02-24-2013, 06:48 PM

Check the mirrors on your visor. Park it in a dark garage and take a look at them. I have seen the switch go bad and leave the lights on constantly. You will never see it during daytime.

**BIGREDDADDY53** · 02-26-2013, 03:06 AM

I pulled all the fuses and ran a voltage check and nothing. But I did find a ground cable running from the hood to the body of the truck that was disconnected I hooked it back up for now till I can get the wright part Mon. I hope this is it. But it may need a new alternator . Thanks for all the info. I will let you know what happens