Hi all,

I'm having an issue with the battery going completely dead on my 2001 4.7L SLT.

The truck routinely sits 7-10 days without use. I have owned it since 2008 and this has never been a problem. Always starts right up. The first time this happened a couple weeks ago I knew the battery needed to be replaced (I never changed it, so over 8 years old at this point), So I simply bought a new one from O Reily's and installed. Now today after 10 days of sitting it is completely dead again. I have checked all accesories, interior lights etc.... I don't think its the alternator because the symptoms seem to be a small draw that completly drains it over a few days time. Any ideas?

I am on my 2nd PCM through autocomputer exchange and wonder if it could be this. Last time the truck was doing strange electrical things which was solved with another PCM.

Thanks

 

I did a draw test on the battery and the amperage went high and actually shorted out my meter so there is something definitley drawing current. Now the fun part will be finding what it is..

 

Keep your meter hooked up (an analog sweeper would be ideal) and start yanking fuses and relays. My first bet is a hung relay since it started abruptly. Something simple like the AC clutch solenoid.

First thing I would pull is the ASD relay. Second would be ABS fuse, third would be headlights/tail lights/cargo lamp (obviously visual check would suffice there). Fourth would be unplugging the connectors from the PCM to rule it out.

 

Thanks for the reply,

Today I borrowed a proffessional multimeter from work and got different results then before. I got around .1-.2 amps with the car completely off. I would think this is normal? Then when I opened the door it went up to about .8amps since the interior lights came on, ran the power seat and it went up to around 4.8amps so it seems to be working correctly, and I seem to be getting normal results.

Now, why is this battery draining? I'm stuck now if it isn't a parasitic draw from a relay or some electrical component as stated above.

 

0.2 amp draw over 120 hours is only 24 amps. Not quite enough to make a huge difference on a large battery, but could be a good chunk of a smaller battery.

 

I have also just tested the alternator and it is putting out a solid 14.1V so I don't think thats the issue. The not fully charged battery went from 12.3V (off) to 14.1V (running).

Maybe it could be the battery itself?

 

yea but to have 2 bad batteries in a row...hard to say. things happen. I've always ran autozone gold batteries. Think 34D ? It's pretty big, fills the whole tray. Course now it's in the bed.

 

Have the battery load tested where you bough it. Also if you disconnect it from the truck will it be charged the next day? If it's dead then it's the battery. The diodes in the alternator may be a culprit, When they go they create a drain(but will still charge the battery but just under normal output). May want to disconnect to alternator fuse and see if it stops the drain.