Battery being drained

[cntinuum]

Been about 2 years since I had to do anything on my 2002 TB. It has a new "feature". With everything turned off, it is draining the battery. When I disconnect the negative lead to the battery, there is quite a bit of sparking. The charging system seems to be working, the battery tested at 13 volts, disconnected from the system, when I got home tonight.
Any thoughts on how to measure the draw when the key of off? Any ideas how to trouble shoot this issue?

I was thinking, if I could measure the draw, I could pull fuses, one at a time and see if this changed the draw. That should isolate which circuit the draw was coming from. Of course that assumes that the draw is coming from a fusable link I can pull the fuse on.
Thanks,
-Dave

 

[Mikie]

Few things first.

1. How old is the battery
2. with the meter what is the voltage at the battery with the truck running
3. have you had both the battery and alternator load tested?

After you do this you can start chasing gremlins

 

[cntinuum]

Few things first.

1. How old is the battery
2. with the meter what is the voltage at the battery with the truck running
3. have you had both the battery and alternator load tested?

After you do this you can start chasing gremlins

The battery is 63 months old on a 100 month battery. All cells are wet.
Running voltage is 14 volts
Have not had a shop load test the battery. If you mean, turning on everything and seeing is the voltage drops, I can do that.

 

[The_Roadie]

Parasitic drains are difficult to track down due to the number of intelligent modules that stay awake for a while even when the ignition's off. Onstar has to stay awake listening for remote unlock commands. The LGM has to stay powered up slightly to listen for keyfob unlock commands. BCM keeps an eye out for security violations.

So pulling the negative battery terminal will always cause sparking unless you let it stay powered off for hours, and that may be the time that drains the battery.

You didn't say how LONG it took for a drain. Measuring the voltage accurately every ten minutes for a few hours can help you find the problem easier than putting an ammeter in series with the battery connection.

That said, if you have an Onstar module, they have a tendency to fail in a way that they don't go to sleep and then they drain the battery overnight. Sometimes 2-3 days. That's why it's important to get an idea how long it takes to drain.

 

[Irishboy02]

That said, if you have an Onstar module, they have a tendency to fail in a way that they don't go to sleep and then they drain the battery overnight. Sometimes 2-3 days. That's why it's important to get an idea how long it takes to drain.

I had this issue on my 05. Not sure what the 02 setup is, if Onstar was even available back then - my 03 sierra doesnt have it

 

[mcc]

I had this issue on my 05. Not sure what the 02 setup is, if Onstar was even available back then - my 03 sierra doesnt have it

My 02 does have Onstar, but it's an older version that only works on analog cell networks. I might as well unplug the module after reading this since it was rendered completely useless when the analog towers were shut down.

GM made digital receiver upgrades available for free with a x-year subscription IIRC.

 

[Irishboy02]

This could be your exact issue then. Analog constantly searching for a signal that isnt there. Similar to leaving a cell phone on with no reception

 

[mcc]

It's possible, but I haven't had any issues with mine- it starts right up even if it's been sitting for a few weeks.

 

[cntinuum]

Thanks Roadie, Mikie, MCC, Irishboy02

Interesting comments, this rig does have OnStar. First issue was letting the rig sit last weekend and wouldn't start Monday morning. Never had any issue since the battery was replaced 05/2007.
Went to O'Reilly's and had the system checked, bad battery. Went to Costco and bought a new battery. Old battery was in the 10V range after we got home from driving around. Amp meter on the dash was reading around 14V when driving. New battery tested at 12.6V. I am sure this is the current issue.

When I changed out the battery, there was no spark when I connected the new battery. What concerns me if there is parasitic drains going on? I am wondering if these will shorten the battery life? Of course, with all our new features, some juice is going to be used to support these functions, security, door locks, OnStar, etc. If OnStar is on a seperate current, I would like to disconnect it. We haven't used it since 2003.

 

[Wooluf1952]

You can pull fuse #27 in the rear fuse block and/or disconnect the wires from the OnStar module under the rear pass. seat.
I just pulled the connectors from the module on my Envoy.

One other thing, 5 years is a long time for a battery in these trucks. You were driving on borrowed time.