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2005 chevy trailblazer_lt
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Discussion Starter #1
I have a 2005 trailblazer. I was having issues with it dying so I replaced the alternator. Continued to have the problems, so I replaced the battery. It STILL dies... I use my remote to lock the doors, then overnight-it dies completely. The remote wont even unlock the doors. I hook it up to a car and jump it- starts right away. I DONT GET IT :( I am so frustrated!!!! :mad: Never had a CB, navigation system, radio system or anything like that installed. However, I have realized that the nights that I dont lock it and activate my alarm--- it doesnt die...??! ANY SUGGESTIONS?!?!?

Thank YOU!!
 

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2005 chevy trailblazer_lt
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Discussion Starter #3
I believe it is the original alarm that came with it--I bought it used, so it may have been previously wired with something different. Im quite sure it is the alarm from the factory.
 

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Classic parasitic drain. It may or may not be related to the alarm arming observation you have, but it takes patience and a meter and some electrcial experience to properly troubleshoot that sort of issue. Sometimes owners get lucky and shotgun their way to a solution by pulling fuses each night, a different fuse every night, until they guess the system that's causing the problem. But that still stresses the battery out a LOT, since batteries not designed for deep discharge like RV or boat use have a shortened lifetime when abused like that.

Why did you replace the alternator? Did it test out bad, or fail to fully charge the battery, or was it a guess? Not a cheap guess.....
 

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2003 chevy trailblazer_ls_ext
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the roadie is right. Diagnosing exactly what and where is draining power will ultimately try your patience, but to confirm that it IS a parasitic drain (seems very likely, though, doesn't it?):

1) get a cheap multimeter, probably even the one from harbor freight for free some months and $3 others will do if you won't need it much, or get a $100 one if you think another day you'll be testing voltages on computer circuits, but you won't need that to find your drain.

2) make sure everything is off, all lights, and with the hood up and the hood light (is there one in a trailvoy?) unplugged to eliminate that draw too, unhook the negative terminal and put your multimeter set to amps in there.

3) someone else help me out here; there IS going to be a normal draw for the sensor that's constantly on, listening for your key, and for the computer RAM that stores the clock and radio stations, and maybe saved seat settings but I don't know. These are low, low draws that would take weeks and weeks to kill a battery. I don't know what's normal for the trailblazer, but I had to troubleshoot my old ford once (found a shorted wire in the tailgate, sheet metal had cut through the insulation from years of rubbing), and normal for that car was .07 amps. It was an older vehicle, a trailvoy will probably be a higher value.
If you're seeing like 1 amp, you've got an issue. Not that you can't already guess it, but, nice to be sure.

4) Now the time consuming part, which component on which circuit?
I'm not very experienced nor very good at fault tracing, so if someone else has a better method, PLEASE chime in,
But what I did was to remove fuses one at a time and with needle probes on my multimeter set to amps, probed across each fuse slot one at a time. Because the dome lights were on because my door was open, I made note of which fuse that was and ignored the amps running through that circuit.

Alternatively, with two people, one person can just leave the ammeter at the battery while you're pulling fuses, and watch for the amps to suddenly dip when you pull the fuse with the short on it [or the dome lights :) ], and then you've found your circuit. I think the trailvoy has a couple fuse boxes, one under the hood, but another under the front seat or something?

Then look up the electrical diagram for that fuse, and individually test the components that run off of it.

When you're done and it's fixed, consider getting a new battery. Deep draining is seriously not good for them, and if it's happened several times now, it's going to be toast sooner than later.
Physical reason why is that you've got metallic lead converting to ionic lead (sulphate?) in solution when you discharge, and then back to metallic lead on the plates when you recharge. But having been deep-discharged, the lead never reforms onto the plates quite the way it was before, and cold-cranking amps --directly dictated by the surface area of the lead exposed to the acid bath-- are forevermore reduced. When all the lead has left the plates when deep discharged, and then reforms again, it will not be as spongy and not nearly as much surface area as it was when the battery was new and charged. Come winter you may have trouble starting in chilly mornings.
 

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3) someone else help me out here; there IS going to be a normal draw for the sensor that's constantly on, listening for your key, and for the computer RAM that stores the clock and radio stations, and maybe saved seat settings but I don't know. ...
There are two kinds of normal currents involved in modern heavily-electronic vehicles. You're right the lowest level resting current is in the dozens of milliamps. I seem to remember mine being around 50ma (0.050 A). Difficult to measure with most cheap meters.

BUT, and this is a huge BUT, disconnecting the battery to insert the ammeter in series with one of the leads (either one actually) will reset almost all of the intelligent modules in the vehicle and will lead to misleading observations. When you remove the ignition key from the TB, the current drain doesn't go to its lowest level right away. There is a RAP (retained accessory power) circuit with a ten minute timer in the BCM (body control module) that if a door isn't opened, will leave the radio and power window circuits energized. There is a longer-term (I think 2 hour timer) that will kill the vanity mirror lights (and reading lights I think) if they're inadvertently left on. To prevent running the battery down.

And one common parasitic current culprit is the Onstar module, that MUST wake up intermittently for a couple of days, for a few seconds each minute, then a few seconds each 5 or 10 minute interval, waiting for a remote unlock signal from Onstar in case you lock your keys inside and call them to save the day. The Onstar module can fail, and not go properly to sleep, and then it drains the battery even for owners who have given up their Onstar subscription. Easy fuse pull to disable just the Onstar module.

HVAC blower modules are always connected to the battery and might leak current, perhaps not enough to spin the fan so you notice its noise, but more than 100mA or so.

Door control modules, liftgate modules, all can fail to go to sleep and be the root cause.

If you arrange the meter to be in series with the battery and make sure the vehicle retains power while you pull the battery lead, by clever use of clip leads while backfeeding the fuse block, for instance, you can measure this higher current while the modules go to sleep over time. For curiosity's sake.

But the easiest way for an inexperienced troubleshooter to do this sort of thing is with a meter set to measure voltage, and just watch for an hour or so after turning off the ignition, each time pulling a different fuse, and if the voltage droops under 12V, put a charger on it to help it survive overnight.

Oh, and discharging or disconnecting the battery carries a risk of killing the misdesigned HVAC actuators when they next recalibrate themselves (subject of many other threads), so it's not a fantastic idea to be pulling the battery cables or totally discharging it more than absolutely necessary.

another under the front seat or something? ...
Rear seat. But good guess. ;)
 

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2003 chevy trailblazer_ls_ext
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thanks for filling in! I'm working as a mechanic now, but I'm still a sophomore in the literal meaning of the word, with the education but not the experience. And I'm finding that there's a lot that's just experience-related, familiarity with certain models and their certain foibles, that classroom training won't cover.
I'm working @volvo, and very often, my mentor will say, "oh, we've seen this before, it's probably the..." or "oh yeah, that's tricky, but this swivel and that extension and you can get to it just so..." I'd figure it out, eventually, but familiarity with the product means a lot.

Those modules that go to sleep over the course of two hours... since you need to open the hood and the passenger door to get to those fuse boxes, will opening the doors wake them up again? If so, is the solution to open the hood and open the passenger door, leave them open and go play computer games for 2 hours, and come back to start your troubleshooting?

I've heard the warnings about disconnecting batteries, but nothing so specific. Good to know exactly why it's a problem, above and beyond just resetting a clock, hahaha. I might read the HVAC threads.

For the OP: When I do batteries @work, I do use a "battery saver." Just a glorified battery itself, but since you may disconnect the old battery @ the terminals, a purpose-built battery saver has either a connection for the 12V outlet in the dash (doesn't always work for all cars, to save the computer settings), or more reliably, the sort of saver that hooks into the obd2 connector and feeds the car power through those.
I believe that the trend is to commit more and more of these saved and learned (e.g., adaptive transmissions) settings to proper flash memory or some such, so that when the battery is disconnected nothing is lost. Hopefully 10 years from now we won't need memory savers?

I don't know how cheap they are, can't be too bad, and I don't know if maybe autozone offers one on rental, which would be nice for you. You only need one for a little while.
 

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2005 chevy trailblazer_lt
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Discussion Starter #8
Thanks!!!!

You guys are awesome!!!! So much info, I dont know where to start :/ Would taking it to a mechanic be a better idea so that they can diagnose it?!
 

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Would taking it to a mechanic be a better idea so that they can diagnose it?!
Don't think we know you well enough to advise. If you're not experienced, or have a structured troubleshooting sort of disposition, you will have very little chance of success without a mentor. Sometimes you can attract a mentor with beer or wine. If you have very shallow pockets, a mechanic may be out of the question. But you might have an adequate budget for user vehicle repair, reflecting the savings you have by not being burdened with a new car payment. We don't know.

We get a lot of posts of the form: I'm flailing about, have no idea what I'm doing, I'm starting to break stuff because I'm guessing or using the wrong tools, but I have no money so don't suggest I get help or buy the right tools, so I'm going to ask some desperate questions.


And then we ask the poster a few essential questions and then they stomp off in a huff because we don't just tell them the answer and we're concealing it for some insane reason. :weird:

For instance, you didn't answer my question about why you changed the alternator, which would have told me a bit about the background of the vehicle and your troubleshooting disposition. ;)
 

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The OP can chime in, but I'd guess because it's a natural conclusion if you don't know how to test one, or aren't aware of other possible causes.
Almost everyone knows that the alternator charges the battery, so if the battery keeps on draining dead, ergo, replace the alternator because the battery must not be getting a charge.

In hindsight that obviously wasn't the issue, but it's a very easy conclusion to jump to.
Heck, when I worked at sears, we WOULD at least test the alternator with a voltmeter, and *finally* before I left they got a proper load tester... but at sears they, too, liked to go with the alternator conclusion, and we never did any tests to consider parasitic drains.
But, that's what you get when your inspection/diagnostics is free and the sears tech isn't being paid more than $.25 to spend time on it.

I actually saw a guy @pepboys looking at batteries and alternators to solve a check engine light! Apparently the dealer had changed the ecm and both O2 sensors and it still hadn't solved the issue (there are of course other causes that an O2 sensor would then register), so he was blindly groping at anything "electrical" like if the battery weren't good enough or the alternator weren't good enough, that would affect the O2 and cause his engine light. Err... I think the OP is smarter than that. But when you just don't know, you can make all sorts of strange speculations, and that story must be among the strangest.


The tools aren't that expensive: we're talking about a voltmeter here!

$100 spent at a dealer to get the circuit tracked down for you and maybe a diagram printed out could be very well spent money, also.

They're going to have to charge you more however if there's any real searching for the particular load or short. Tearing apart trim takes time!
But if they can tell you the circuit that's drawing power and the color of the wire to look for, the loads that are on it, that'll get you started.

Batteries aren't cheap, either, mind you!

And hell, maybe you'll find out and decide that it's a nonessential circuit and just choose to pull that fuse for the time being.
 

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Draining Battery

I have a 2003 envoy, I bought it second hand and it had a remote starter already in it, when I got it i used the remote for a few weeks and then noticed that my battery was draining and dying fairly quickly, ended up removing the fuse for the starter and replaced my alternator and battery, had my second battery and it froze solid, replaced that, now on to my third battery and if I don't unplug the battery or have a trickle charge on it over nite it dies, thinking it is my cluster but what I have seen on the internet regarding this vehicle the cluster only affects the speedometer which has never been an issue. I'm getting really frustrated with this and have wasted numerous amounts of time and money on it and want it fixed so i can get rid of this piece of junk. Must also add the previous owner also had a draining battery issue as well and we knew we would have to replace the battery eventually but I have gone through 3 batteries now. and still no idea what is causing this issue.
 

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2002 gmc envoy_sle
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2002 Envoy Battery Drain Overnight

There are two kinds of normal currents involved in modern heavily-electronic vehicles. You're right the lowest level resting current is in the dozens of milliamps. I seem to remember mine being around 50ma (0.050 A). Difficult to measure with most cheap meters.

BUT, and this is a huge BUT, disconnecting the battery to insert the ammeter in series with one of the leads (either one actually) will reset almost all of the intelligent modules in the vehicle and will lead to misleading observations. When you remove the ignition key from the TB, the current drain doesn't go to its lowest level right away. There is a RAP (retained accessory power) circuit with a ten minute timer in the BCM (body control module) that if a door isn't opened, will leave the radio and power window circuits energized. There is a longer-term (I think 2 hour timer) that will kill the vanity mirror lights (and reading lights I think) if they're inadvertently left on. To prevent running the battery down.

And one common parasitic current culprit is the Onstar module, that MUST wake up intermittently for a couple of days, for a few seconds each minute, then a few seconds each 5 or 10 minute interval, waiting for a remote unlock signal from Onstar in case you lock your keys inside and call them to save the day. The Onstar module can fail, and not go properly to sleep, and then it drains the battery even for owners who have given up their Onstar subscription. Easy fuse pull to disable just the Onstar module.

HVAC blower modules are always connected to the battery and might leak current, perhaps not enough to spin the fan so you notice its noise, but more than 100mA or so.

Door control modules, liftgate modules, all can fail to go to sleep and be the root cause.

If you arrange the meter to be in series with the battery and make sure the vehicle retains power while you pull the battery lead, by clever use of clip leads while backfeeding the fuse block, for instance, you can measure this higher current while the modules go to sleep over time. For curiosity's sake.

But the easiest way for an inexperienced troubleshooter to do this sort of thing is with a meter set to measure voltage, and just watch for an hour or so after turning off the ignition, each time pulling a different fuse, and if the voltage droops under 12V, put a charger on it to help it survive overnight.

Oh, and discharging or disconnecting the battery carries a risk of killing the misdesigned HVAC actuators when they next recalibrate themselves (subject of many other threads), so it's not a fantastic idea to be pulling the battery cables or totally discharging it more than absolutely necessary.

Rear seat. But good guess. ;)
Thanks to this site and these threads I was able to diagnose my battery drain as the OnStar module staying active. Pulled the fuse (I think #11 under the rear seat) and the problem is resolved (for now... knock on wood). Ironic a system that is supposed to help creates unreliability in the vehicle.:)
 

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Thanks to this site and these threads I was able to diagnose my battery drain as the OnStar module staying active. Pulled the fuse (I think #11 under the rear seat) and the problem is resolved (for now... knock on wood). Ironic a system that is supposed to help creates unreliability in the vehicle.:)
I've asked this question a couple times( 1st which fuse is the onstar that leaks voltage all the time) seems that there is 2 circuits.and 2 what other things are attached to that circuit that won't work with that fuse out? Thanks!
 

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The fuse is actually #27, description is "OH batt OnStar". I have not noticed anything else not working, will post back if/when I figure out what OH Batt does.
 

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The fuse is actually #27, description is "OH batt OnStar". I have not noticed anything else not working, will post back if/when I figure out what OH Batt does.
Thanks for the update (number 27) I'm semi handicap and don't drive as much so it'[s a big drain and makes batteries last shorter. Thanks again.
 

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C
the roadie is right. Diagnosing exactly what and where is draining power will ultimately try your patience, but to confirm that it IS a parasitic drain (seems very likely, though, doesn't it?):

1) get a cheap multimeter, probably even the one from harbor freight for free some months and $3 others will do if you won't need it much, or get a $100 one if you think another day you'll be testing voltages on computer circuits, but you won't need that to find your drain.

2) make sure everything is off, all lights, and with the hood up and the hood light (is there one in a trailvoy?) unplugged to eliminate that draw too, unhook the negative terminal and put your multimeter set to amps in there.

3) someone else help me out here; there IS going to be a normal draw for the sensor that's constantly on, listening for your key, and for the computer RAM that stores the clock and radio stations, and maybe saved seat settings but I don't know. These are low, low draws that would take weeks and weeks to kill a battery. I don't know what's normal for the trailblazer, but I had to troubleshoot my old ford once (found a shorted wire in the tailgate, sheet metal had cut through the insulation from years of rubbing), and normal for that car was .07 amps. It was an older vehicle, a trailvoy will probably be a higher value.
If you're seeing like 1 amp, you've got an issue. Not that you can't already guess it, but, nice to be sure.

4) Now the time consuming part, which component on which circuit?
I'm not very experienced nor very good at fault tracing, so if someone else has a better method, PLEASE chime in,
But what I did was to remove fuses one at a time and with needle probes on my multimeter set to amps, probed across each fuse slot one at a time. Because the dome lights were on because my door was open, I made note of which fuse that was and ignored the amps running through that circuit.

Alternatively, with two people, one person can just leave the ammeter at the battery while you're pulling fuses, and watch for the amps to suddenly dip when you pull the fuse with the short on it [or the dome lights :) ], and then you've found your circuit. I think the trailvoy has a couple fuse boxes, one under the hood, but another under the front seat or something?

Then look up the electrical diagram for that fuse, and individually test the components that run off of it.

When you're done and it's fixed, consider getting a new battery. Deep draining is seriously not good for them, and if it's happened several times now, it's going to be toast sooner than later.
Physical reason why is that you've got metallic lead converting to ionic lead (sulphate?) in solution when you discharge, and then back to metallic lead on the plates when you recharge. But having been deep-discharged, the lead never reforms onto the plates quite the way it was before, and cold-cranking amps --directly dictated by the surface area of the lead exposed to the acid bath-- are forevermore reduced. When all the lead has left the plates when deep discharged, and then reforms again, it will not be as spongy and not nearly as much surface area as it was when the battery was new and charged. Come winter you may have trouble starting in chilly mornings.
  1. OK question here, with battery disconnected and multimeter in place in a series from batt post to cable a multimeter won't let power thru to load what's drawing so how is the meter gonna read anything different?
  2. With a test light acting as a fuse basicly you can still power whatever drawing therefore you can visibly see it u powered when you pull fuses and light goes out... Am I wrong???
 
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