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'08 TrailblazerSS
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OK this can be a whole mess of problems rolled into one. You can and probably do have an account setup issue with Onstar, but we'll get to that later.

First and foremost forget everything with the onstar. You have a paracitic drain. Your truck is draining more power than spec when it's supposed to be powering down for minimum power loss.

It can be anything causing a paracitic draw. The most common that I find which are the culprits are BCM, Radio, Onstar in that order. There are other things as well such as seat modules, any computer in the truck, seat heaters, window switches, any number of things that can cause a draw. There are tests that you can to do to, first, determine the rate of the draw, and second, to isolate the draw. So, yes the Onstar is one of about 40 different reasons you can have a draw on the battery. The fact that your onstar is not connecting can mean something but then again it can also mean your account is not fully functional which has nothing to do with the module itself but can be on Onstar's (the facility) end.

Pulling the fuse does not "reset" onstar and does nothing but removes power from the module. When you reinstall the fuse, the module contunues on as normal.

I can explain how to do a paracitic draw test, but it's very hard to translate and teach this procedure over text and is very time consuming. You also need the proper DVOM to do it with.

Now the actual repair may vary depending on where the draw is isolated to. Some modules might need a software update, some may need to be replaced entirely. The bad part is that there isn't much you're going to be able to do about it in your driveway if you need to reprogram a radio, or a BCM, or replace one of those units where it will still need to be programmed. There are a bunch of TSBs for paracitic draw issues and all of them start by doing the paracitic draw procedure.

You cannot go by a fuse arcing when reinstalled on a module (computer) to determine if the module is pulling too much power. There are a bunch of capacitors inside of those modules that will surge when you power up the circuit. Besides, the onstar fuse may power up more than just the onstar module.

So the quick and dirty test is, charge the battery up fully, and I mean peak charge it. If you really suspect the onstar module, then unplug the connectors at the module. Wait and see if the battery goes dead over a few days. Don't touch the truck, don't open the door, don't turn on the key, just wait two days and see what it does. Even if we determine it's the onstar module, you'll still have to bring it in to have the module programmed and the account set up.

So in short, I can tell you how to test for it, it's not easy, it can be time consuming, you need the right equipment and you will most probably end up at the dealership anyway to have the module installed and programmed.
 

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The one and only JJ
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14,071 Posts
Yea Jay I'm with ya as my SS sat at Dealership for 1 week until they determined it was my Seat Module. I say take it to them and have them determine what it is unless u like dealing with issues which I dont lol.
 

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Trailblazer SS
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JJ... I bet u had cum come out of your ass and good some of the wiring wet and cause a short
 

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TrailBlazer SS AWD
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Discussion Starter · #24 ·
Thanks Alot Jay. I Am An Electrical Technician And Know How To Read A Draw With My DVOM , So You Don't Have To Get Into The Details For Me There. If you Could tell me What The Draw Should Be With The Key Off That Would Be A Great Starting Point For Me. I Will Try To Find The Time This Weekend To Measure The Amount Of Draw And The Time Frame In Which It Happends. The OnStar Fuse Does Power More Than Just That, It Also Powers My BlueTooth Adapter, But I Had The Dealership Install My BlueTooth And Aftermarket Radio, So It Should All Be Covered Under Warranty. I Do Have A Full Active Account With OnStar And Have From The Night I Drove It Off The Lot And Am All Paid Up Until Feb 2011. I Usually Get My Monthly Reports But Haven't Since This Issue Started, And This Issue Started When I Was Supposed To Get My Last Report. Thanks For The Input Jay.
 

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'08 TrailblazerSS
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You need a DVOM capable of recording min max and avg of a DC milliamp draw. The meter needs to have ability to stay awake and record over a day or two straight and have enough resolution to measure from 10 amps or so down to 2 ma or so.

A FLUKE 87 or 88v DVOM is perferable.

To find the max allowable paracitic draw you take the reserve capacity of the battery and divide it by 4. Stock spec battery has a reserve capacity rating of 115 mins.

Stock spec.
115 /4 = 28.75 ma max allowable draw. I think up to 30 / 35 ma draw is acceptable.

What's the reserve capacity rating of your 1000 CCA battery? Or, what is the amp hour rating of the 1000 CCA battery (and divide that by 2.4)? We need this to figure out the max allowable draw for the battery you have installed.

There is a procedure to this, you can't just jump right in and start measuring draw so let me know when you have the info above we'll proceed to the next step.
 

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TrailBlazer SS AWD
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Discussion Starter · #26 ·
Thanks Again Jay. I'm Sure Ultimately I Will Be At The Dealership To Either Replace Or Reprogram The OnStar Module Or Update Whatever Needs Updating. Atleast Now I'll Have A Rundown Of What I Can Tell Them I've Already Done To Save The Tech Some Time.
 

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Discussion Starter · #27 ·
I Went To Start My SS This Morning And It Barely Started. So I drove It Around For About A Half Hour And Let The Battery Fully Recharge. I Then Pulled The Fuse To The OnStar. I Will Not Be Driving It Until Saturday, I'll See If My Drain Issue Goes Away. Normally My Battery Will Go Completely Dead After Two Day Of Not Starting, So After Four Days If It Starts Right Up I'll Know For Sure It's That Circuit. If It Still Dies Now I Have The Info I Wanted To Further Trouble Shoot It.
 

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'08 TrailblazerSS
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You should peak charge the battery first with a battery charger then unplug the module. Driving it around for a few mins is not enough to recover the battery. The normal < 30 ma drain may kill an undercharged battery and prove an inconclusive result. It's much better to start off with a fully hot battery.
 

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TrailBlazer SS AWD
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Discussion Starter · #29 ·
Recently After One Whole Day, Two At Most My Battery Was Going Completely Dead. My OnStar Wasn't Working Properly Either, So I Assumed It Was The Problem. After Getting Detailed Info As To What To Look For I Planned On Diagnosing It Today. I Took The Fuse For The OnStar Out Wednesday Morning And Haven't Tried To Start It Until Today. Well, I Just Went Out To Start It And She Started Right Up. I Knew My OnStar Wasn't Working Proplerly, Now I Know It Was Also The Cause Of My Voltage Drain. Hopefully This Can Now Be An In & Out Replacement Or Update Service Call ANd I Won't Have To Leave My SS At The Dealer.
 

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07 2wd TBSS
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I took the fuse out 2 but still was dead after it left me hanging at work yesterday after work I said fuck run in get a new Delco 800 CCA battery and the thing started right up am still gonna give optima one more try and get that red top
 

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TrailBlazer SS AWD
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Discussion Starter · #31 ·
I Dropped Off My TBSS At My Dealer On Monday Morning. The Dealership I Bought My SS From Offers A Loaner Vehicle If You Want It When They Do ANY Work On A Vehicle You Purchased From Them, Even If Your Just Getting An Oil Change. So I Dropped Off My SS 7:30 am Sharp And Got To Personally Speak To The Tech Who Was Going To Work On My Baby. I Told Him My Buddy Jay (JAY4SPEED) Is A GM Tech At Another Dealership And We Had Diagnosed The Problem, My OnStar. It Had Not Been Functioning And Ever Since I Stopped Receiving My Monthly Reports My Battery Going Dead Ever Other Day If I Didn't Start It. I Explained How We Metered For A Draw With My DVOM And Found A Higher Than Spec Draw Went Away When The OnStar Fuse Was Removed. I Had The Fuse Out For A Few Weeks Now And My Battery Hasn't Died Since. I Still Had To Leave It Overnight Because That Is The Troubleshooting Process By The Book. I Got A Call Last Night That My OnStar Unit Was "Internally Shorted", So They Replaced It. Picked My TBSS Up This Morning, 7:30 am Sharp Again. Gave Back The EXTREMELY SLOW 06' Malibu Loaner Car And Back Behind The Wheel Of My Beast. On The Drive Home I Contacted OnStar And Had Tech Support Transfer My Account To The New Unit, 10 Minutes Later Everything Was Working 100% Again. Best Part, All Covered Under Warranty. All It Cost Was $4.00 In Gas I Put In The Loaner Car To Go To And From My House.

I'm Loving My Dealership And My GM Warranty. So Far Ever Experiance Has Been A Pleasant One Since The Day I Met My Salesman.

Lookinng For A GM Vehicle In The Long Island Area? Contact My Salesman.

Andrew Hannon
[email protected]

East Hills Chevrolet
1039 Northern Blvd
Roslyn, NY 11576
(516) 869-8100
 

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where is the onstar module located....is it easy to unplug? I think I have a paracitic draw issue and I don't use onstar so I wanna unplug it...my battery goes dead after about a week sitting.
 

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TrailBlazer SS AWD
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Discussion Starter · #33 ·
If You've Added Anything To The SS Recently (Anything Electronic) I Would Start With That First. If You Want To Find Out If It Is The OnStar Causing It You Can Pull The Fuse. Flip Open The Rear Seat On The Drivers Side, Pull The Cover To The Fuse Panel, Read The Cover To Find The OnStar Fuse And Just Remove It. Give It A Week, If The Battrey Doesn't Die Then That Was You Issue.
 

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If You've Added Anything To The SS Recently (Anything Electronic) I Would Start With That First. If You Want To Find Out If It Is The OnStar Causing It You Can Pull The Fuse. Flip Open The Rear Seat On The Drivers Side, Pull The Cover To The Fuse Panel, Read The Cover To Find The OnStar Fuse And Just Remove It. Give It A Week, If The Battrey Doesn't Die Then That Was You Issue.
hmm I have it tuned, efans, pcmforless battery cable upgrade, viper 5902 and the aeroforce interceptor...maybe one of those? I noticed this problem starting around last winter and the battery got drained about 3 or 4 times. I figured it just needed a good charging and once i was able to do that it seemed fine but now i let it sit about 2 weeks and it died again. I'm planning on putting a new battery in but i'd like to see if I can figure out if there's a draw issue before hand. I'll try finding the onstar fuse...do u happen to know what # it is? Thanks for the help :)
 

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Trailblazer SS AWD
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I'm having an issue with my battery now that the truck sits. sounds like the same problem you had vin, every two days, thing just dies.

which fuse is the onstar fuse? i'll see if that works.

i thought it was the rear air bag comp fuse, i pulled that, it still died
 

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TrailBlazer SS AWD
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Discussion Starter · #36 ·
It's A Little Fuse Under The Rear Drivers Side Seat. The Cover Will Tell You Which Fuse It Is. I Believe It Was A 10A Yellow Fuse.
 

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Trailblazer SS AWD
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It's A Little Fuse Under The Rear Drivers Side Seat. The Cover Will Tell You Which Fuse It Is. I Believe It Was A 10A Yellow Fuse.
Ok, just pulled it. It's a 10A Red Fuse. I'm going to charge the battery fully and see if it holds the charge for the next few days
 

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Trailblazer SS AWD
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waited a few days after pulling the red fuse, went to start it, dead truck.

tested battery. battery was bad. went and bought new optima. gonna see how long it lasts
 
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