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2004 gmc envoy_sle
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Discussion Starter #1
Hi Guys
2004 envoy batteray keeps going dead i checked batteray and its isstill good
no lights on in car radio off ,key off nothing on but Batt gos dead any thoughts ??
 

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Well - we know that the ECM/BCM and other onboard computers (eg: radio, USB chargers, Bluetooth, etc) need their KAM voltage and they always draw current - but it is so insignificant that it really shouldn't draw a battery down in maybe a month or two --- so that's likely not a/your problem.

Let's start at basics here so we can establish a logic tree and not jump all over the place with ideas and not using good diagnostic technique.

Since I am not THERE - I cannot make these preliminary tests - so you will have to do it and report back so we can fix this problem. .

OK --- so WHAT can draw current enough to discharge --- what YOU say is a good battery?

If this is an overnight problem, and you're SURE that the battery has never been dead enough to ruin it.... then I'd disconnect the alternator B+ cable and see if the battery survives an overnight test.

The alternator - if it has one or more shorted diodes, can draw the battery to it's knees in a few hours. BUT there would be some heat generation to actually consume the charge in the battery. If the alternator's warm 'way after the rest of the engine has cooled down - that's a clue.

But let's explore the battery for a moment ---> IF it has been drawn below 10.3VDC, it is suspect all by itself from now on. Modern batteries must be above a threshold voltage or they chemically damage themselves and they never are trustworthy from that point.

  • You MIGHT get away with keeping a damaged battery in your vehicle and it MAY start the engine for a WHILE --- but it will suddenly stop functioning. The only battery design that can handle serious depletion of it's charge is a DEEP CYCLE/RV-style battery - unless it also gets frozen while it's discharged.
FWIW: a fully charged battery can take some seriously low temperatures without freezing. If only half-charge, most batteries will freeze at or near 25F. Once frozen - they are junk.

Then - let's test the alternator by hooking a DVM to the B+ alternator lug.

Start the engine and test for AC (alternating current) on the DC-side.

There cannot be more than 0.015VAC on the DC charging wire at the alternator.

Don't run this test at the battery POSITIVE connection. You will get a dampened reading that will make it kinda hard to interpret.

Run the test AT the alternator.

Please RSVP your results.

.
 

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2003 chevy trailblazer_ls
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Definitely check your voltages with a multi meter. I had a similar issue and was about to be on my 4th battery in 3 years. Started checking voltages and it was my battery terminal bolts. I was getting inconsistent voltage readings at them. Replaced them and perfect voltage readings now after a full charge of the battery. If you have problems jumping the truck too, could lead you down a similar path. The bolts get corroded and don’t carry enough juice.
 

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2006 gmc envoy_sle
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Not sure if you changed any components, but I put a new liftgate control module on my 06 and didn’t get it programmed right away. It drained the battery several times before I took it in to get programmed at the dealership. No more issues.
 

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Just buy a new cluster. Had the same problem for about 3 years , i tried everything, until i changed the speedometer cluster, after that problem solved. Hope this help.
 

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2004 gmc envoy_slt
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A parasitic drain test needs to be done on the electrical system to determine first if there is a parasitic drain taking place, and if so, isolating it to a particular device.
 

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I wasn’t suggesting to just start changing parts.... I changed my lifgate control module due to failure. The new unit was draining the battery until it was programmed.
 

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There's always a small KAM drain on the battery from various modules, computers and even USB chargers left inserted in power outlets.

A slight spark when you hook up the battery is normal, so don't see that and panic. It's just devices taking a small shot of the battery voltage supply.
 

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2004 chevy trailblazer_ls
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So other than the obvious, bad actual battery, incorrect battery (too small), bad alternator, bad grounds, etc... I helped a buddy fix his issue just like this and he had tried every single unlikely issue first and insisted the stuff i mentioned was fine... Well, after he gave up, I ended up finding that his battery was the wrong CCA rating AAAAAND the battery ground terminal bolt was stripped out...And poof, it was fixed. I did however find that his auto climate control sensing fan in the B piller by the drivers head was bad. Caked with fuzz.
 

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Top 5 reasons a trailblazer has weak or dead battery per alldata is due to 1- instrument cluster/replace 2- battery/replace 3- blower motor speed controller/replace 4- alternator/replace 5- liftgate module/ replace.
 

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My parasitic draw is .056 amps. Is that considered normal? I thought I read TBs get darn close to zero.

I should add, this after the initial drop in amps after reconnecting the battery using the multimeter leads. It initially read about 1.0 amp then after about 30 seconds dropped to a static .056 amps. Do I need to wait longer to allow more systems to "go to sleep"?
 

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The ECM always takes a constant sip from the battery... and I am not familiar with the BCM, this TCM and if there's any other xCM units in this vehicle taking their own sips too.

I'm pretty sure the radio has a KAM... so there's that too.

Pulling fuses one at a time ... may not get you the results you want either.

Tgere has to be a chart SOMEplace with acceptable current draw... but I know a GM left in a barn for a a snowbird for when they return.... will almost always have a dead battery in spring without at LEAST a float charger on it.

Alternators of late... have been a very big problem with killing batteries. You might want to start by taking off the B+ cable from the stud on the alternator... and check for a parasitic draw that magically disappears.
 
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