Battery Draw? Alternator Farked?

[Gump2773]

Just started happening that if I leave my car sitting for 12 or more hours the battery is dead when i come back. Had a load test done and the readings all came out ok.
Electrical problems are not what I need at the moment. Any clues as to what may be happening or where I should check next?

Amp - Xm Radio - GPS - Head Unit - Dome Lights All turn off when the car is shut off.

 

[Denali n DOO]

Just started happening that if I leave my car sitting for 12 or more hours the battery is dead when i come back. Had a load test done and the readings all came out ok.
Electrical problems are not what I need at the moment. Any clues as to what may be happening or where I should check next?

Amp - Xm Radio - GPS - Head Unit - Dome Lights All turn off when the car is shut off.

Do you have On Star? My battery was being drained by a faulty On Star module. Pic4935 VCIM defective, parasitic draw. They also said the dead battery caused 25 transmission codes to be set.

Just a thought...

 

[Gump2773]

i do not have onstar.

 

[The_Roadie]

Parasitic drains have been discussed along with successful troubleshooting tactics before. They're among the most annoying and subtle things to track down without careful, structured troubleshooting.

Do you have a meter and know how to use it?

Otherwise you're reduced to pulling fuses one at a time and waiting 12 hours to see if the problem goes away. Could take a month to figure out WHICH fuse is on the troublesome circuit, and THEN you have to figure out which component on that circuit is the culprit.

Of course it could be just an old battery self-draining, and the load test you had done is NOT a valid self-drain test. All it does is tell you how much current it will deliver in a starting situation. How old is your battery?

 

[Gump2773]

4 months old for the battery. I just took it to an auto center here and they did a charging system check. Everything came back ok. They did say they could monitor it all day and tell if it were taking on a load while sitting, but then the expensive work would be tracking it down from there. For them to trace the issue I would be looking at hundred and hundreds of dollars. Im not ok with that.

As far as completely knowing my way around with a multi meter the answer is no.

 

[Wooluf1952]

If it happens any time it sits for 12 hours, this would be my way of finding the drain:

Disconnect the 125 amp Maxi fuse. If it stops the drain, the problem is in the rear fuse box. Reconnect the maxi fuse.

Pull half the fuses from the rear fuse box. If that stops the drain, one of those pulled is the problem. Keep track of the fuses you pulled and next time only remove half of those.

Just keep removing half of the fuses each time and you will eventually find the problem.

This way you don't even need a meter. However, this only works if the battery drain happens any time you let it sit for 12 hours as you said.

This is time consuming, as Roadie stated, but it is a lot cheaper than having a mechanic do it.

 

[kartracer_3]

You do not need a multimeter or have to wait 12 hours per fuse. All you need is to be careful and have a decent test light. I will post another how to after while. Stay tuned.................

 

[The_Roadie]

For them to trace the issue I would be looking at hundred and hundreds of dollars. Im not ok with that.

As far as completely knowing my way around with a multi meter the answer is no.

We'll do what we can to help you, but do you have any buddies who know electrical troubleshooting and own a meter? I personally wish I could save money and do my own haircuts, but alas, sometimes you just have to suck up and outsource what you can't do yourself. Or purchase the training as an investment. People who know this stuff deserve to be compensated.

 

[kartracer_3]

Get yourself a good fully charged battery because draining them completely time after time is very rough on them.
Disconnect the negative battery cable .
Install test light between cable and battery. This may take some fiddling . Sometimes easier to put the point of the test light in the cable and the clip on the negative battery post.
At this time your test light should be lit . Either dim or bright.
This is where you need to be careful.
Momentarily touch the cable {pointy end of the test light} to the negative battery post or test light ground. This will discharge the systems, If you are worried about harming the ECM I suppose you could pull the fuse to it before starting this test.
If the test light goes out completely then you do not have a drain.
If the light stays on then you have a drain. If you have a monster drain and the light is very bright DO NOT REPEATEDLY TOUCH THE 2 ENDS OF THE TEST LIGHT TOGETHER. These late models do not like sparks.
With light on bright or dim{drain small or large } you can start pulling fuses. I would probably start with the under hood fuse block first then work your way to the one under the rear seat.
When you pull the fuse in the circuit that is draining the battery the light will go out.
After you locate the drain circuit find a wiring diagram for that circuit.
Common drains I have found are power seats, power windows,heated /power mirrors,power door locks,fuel pumps,audio/video incorrectly installed, ALTERNATORS{THAT ONES A BIGGY},Interior lights, under hood lights.
Hope this helps and let us know the fix
KR3

 

[The_Roadie]

Note that the test light technique may give confusing results due to some intelligent modules not turning instantly and fully off when you turn off the ignition. They go into a resting state waiting for timers to count down, such as the RAP (Retained Accessory Power) and OnStar and the LGM which has to listen for remote keyfob commends. KR3 - have you used this technique a lot on GMT360s, or mostly other platforms?

 

[MAY03LT]

They did say they could monitor it all day and tell if it were taking on a load while sitting, but then the expensive work would be tracking it down from there. For them to trace the issue I would be looking at hundred and hundreds of dollars. Im not ok with that.

I'm not ok with that and it's not even my truck! The only reason that they'd have to monitor it all day is if it passed a preliminary key off draw test. To throw out a "hundreds and hundreds of dollars" line without a preliminary test says to me that they're scared to look at it.

I threw out the test light back in 03. Too unreliable when some manus can have up to .05A as "normal".

 

[The_Roadie]

I threw out the test light back in 03.

I've never even owned one. I built my own Heathkit multimeter in junior high. Sadly, it broke a long time ago and I used a classic Simpson 260 for years after that.

View attachment 21303

 

[Gump2773]

I'm not ok with that and it's not even my truck! The only reason that they'd have to monitor it all day is if it passed a preliminary key off draw test. To throw out a "hundreds and hundreds of dollars" line without a preliminary test says to me that they're scared to look at it.

It did pass the tests and he said there had to be some sort of draw. And when asked how much to diagnose and fix the problem he said they would have to let it sit and watch the draw and then trace wires and thats where the large costs would start to add up.

I unplugged the battery and metered it.. got 12.64 V let it sit for 5 hours and just tested it again at 12.54 V so Im ruling out the bad battery idea I think.

 

[MAY03LT]

It did pass the tests and he said there had to be some sort of draw. And when asked how much to diagnose and fix the problem he said they would have to let it sit and watch the draw and then trace wires and thats where the large costs would start to add up.

I unplugged the battery and metered it.. got 12.64 V let it sit for 5 hours and just tested it again at 12.54 V so Im ruling out the bad battery idea I think.

I mean a key off draw test, not the battery test. With all loads off, the meter (set to amps) is placed in series with the negative battery terminal. So, with the negative battery lead disconnected, one lead of the meter gets connected to the negative battery terminal (I use an adapter for this) and the other lead goes to the negative battery cable. This will tell you how much draw there is. For me, there are only two scenarios. Either the draw is high, which would mean the problem could be traced immediately; or the draw is within spec/normal, meaning there may be a module or component that wakes up unexpectedly. The latter is much tougher to catch then the former, but in either case, I don't even give an estimate on time until the preliminary test is done.

Are you saying the battery volts dropped when it wasn't hooked up?

 

[Gump2773]

Are you saying the battery volts dropped when it wasn't hooked up?

Well if you wanna call it that. Unhooked neg terminal and tested. (12.64 v)

5 hours later... (12.55 v)

 

[Chickenhawk]

Battery voltage is not linear, and that drop in 5 hours seems a bit much. I know you had the charging system tested but I am still suspicious about the battery, especially because you said it is almost new. (Because batteries are an electro-chemical reaction, they tend to fail quite early or last years. Inexpensive batteries tend to have higher initial failure rates because the plates are much thinner than quality batteries, and they can survive voltage tests and even some load tests, and still have a bad plate. I would be inclined to have another load test down and maybe even check the specific gravity of each individual cell if possible.)

While this does not seem likely with a new battery and a professional shop who has tested your ignition system - and load-testing the battery would be the first item on their checklist - at least it eliminates the likeliest cause and the easiest and cheapest to test first.

I am always suspicious of battery more than 5 years old or newer than 4 months old. Call me a cynic.

 

[The_Roadie]

If the initial 12.64V was taken just after the engine was turned off, it's possible that the voltage was slightly elevated from "surface charge." (A fruitful search phrase) Battery tutorial sites recommend loading it with the engine off for a couple of minutes with the headlights on, to remove the surface charge. Then disconnect it and check the voltage. Wait 6-12 hours and check the voltage again. 100mV is a reasonable value for this misleading surface charge.

 

[kartracer_3]

Gump, where did you buy your battery ? It being 4 months old they should exchange it with no ?'s asked. If they make a fuss tell them the dam thing is bad and demand your money back so you can go some where and get a real one.
Trust me that is the first thing I would do. I have bought numerous bad batteries straight off the shelf brand new. Even if I was sure I had a drain I would do this . At the very least borrow a known good one from another car or a buddy.

Roadie, yes , in fact I have used this method on my 03 TB when I first bought it while installing a new battery, in that case I did not have a drain . The battery was going on 5 years old and needed replaced . Come to think of it the symptoms were a lot like Gump's. Let the TB sit over night and it would not start. After charging the battery a couple of times and load testing it , which it passed by the way with flying colors more than a few times , I decided to just go get another battery. Now don't get me wrong I own a multi meter also and use it almost as much as I use the old snap on test light.
Yes you have to keep bulbs in it and a good lead on it at all times. I suppose its a habit I have got into over the years good or bad it works for me. Bottom line is what ever floats your boat.

I mainly was just trying to make the point that you did not have to have a meter to diagnose a drain nor should you have to spend hundred and hundreds of dollars to have someone do it for you, that is INSANE.
Now I might charge you hundreds to find an intermittent drain.

After repairing vehicles for many many years I have got in the habit of checking for a drain when installing a new battery regardless of any of the symptoms or what anyone says. I absolutely HATE comebacks and by getting in the habit of this I may have saved myself 8-10% of them when installing batteries.

 

[Gump2773]

Update:

Took the TB to my regular mechanic this morning. He in fact found a draw of .06a. After troubleshooting for a bit he couldnt find the draw. So I made an appointment for all day wednesday.
As I left the shop i could immediately hear problems. The fan clutch wasnt working properly and the TB sounded like a jet engine as I scooted down the road. Turned around and went back, he said "ahh thats normal, Turn off your AC and it will go away". 22 miles home it didnt go away. And to beat all that, half way home the check engine light came on and the TB seemed to be taking FOREVER to shift. Why me!

So parked till wednesday I guess.

 

[kartracer_3]

Update:

Took the TB to my regular mechanic this morning. He in fact found a draw of .06a. After troubleshooting for a bit he couldnt find the draw. So I made an appointment for all day wednesday.
As I left the shop i could immediately hear problems. The fan clutch wasnt working properly and the TB sounded like a jet engine as I scooted down the road. Turned around and went back, he said "ahh thats normal, Turn off your AC and it will go away". 22 miles home it didnt go away. And to beat all that, half way home the check engine light came on and the TB seemed to be taking FOREVER to shift. Why me!

So parked till wednesday I guess.

So this "regular mechanic" added more issues ? Is he ASE certified ? Have you done business with him before ? Maybe ask around and if he seems to be on the up and up give him a shot to repair it. He may have been to much in a hurry to help you and left something unplugged causing the fan to stay on and the CEL to come on.
let us know what the fix is
KR3

 

[MAY03LT]

Now I might charge you hundreds to find an intermittent drain.

And that aint no bs. There's a Lincoln at my work with an intermittent drain that has close to 7 hours sunk in it. At the shops rate of $80/hr, well, you can see that problems like that can become very costly very quick.

He in fact found a draw of .06a. After troubleshooting for a bit he couldnt find the draw.

Did he check your aftermarket stuff? Anything that's powered outside of the fuse block(s) can pass the traditional fuse pull test.

 

[Chickenhawk]

Either a failed battery or a failing ignition switch can cause random and obscure electrical problems like these.

 

[kartracer_3]

And that aint no bs. There's a Lincoln at my work with an intermittent drain that has close to 7 hours sunk in it. At the shops rate of $80/hr, well, you can see that problems like that can become very costly very quick.

I can relate to that May, I had a Lincoln eat my lunch for 4 days on an intermittent drain. Turned out to be a trunk light circuit.

 

[Gump2773]

Ok with my multimeter set to dca i meterd it inline with the neg bat cable and terminal. I see a draw of 0.04 ... pulled every fuse under the hood box and the rear seat box and still a 0.04

If it were one of those circuits it would have dropped to 0 when i pulled the fuse correct?

Where do I check next? I did check the inline fuse for amp and saw no change as well.

 

[The_Roadie]

0.04A is 40mA. If the typical battery has 100 Amp-hours of storage, that amount of current would take 3 months to drain the battery. I'm guessing you disconnected the battery cable so the vehicle powered off, then put the meter in the circuit? That may have reset whatever module is causing the drain. If you can, get the meter connected to the battery terminal and cable connector BEFORE disconnecting it, so the meter gets inserted in the circuit without letting the vehicle go dark for an instant.

In our platform, parasitic drains are more likely to be intelligent modules failing to go to sleep, than it is to be an inadvertent glove box light. To drain the battery in 12 hours implies a drain of 5-10A, which is more than the typical glove box light anyway. Or a failed HVAC blower speed control module (on an EXT in the rear or a regular vehicle in the front with the digital/automatic HVAC controls).

 

[Gump2773]

lol well shit.. im so not mechanically inclined

 

[The_Roadie]

We're trying to help you save $$$. How can we help?

If you filled out the vehicle profile, and you had an EXT, we might be able to guess better. Any chance it's your HVAC blower and it may be intermittent, so it doesn't drain the battery every time? Or is your problem consistent and the drain happens 100% of the time?

The slow way to diagnose it might be the path you need to take. Pull one fuse a day when you shut it off. Measure the voltage. Go back in 3 hours and see if the voltage droops significantly. If it does, slap on a battery charger so it doesn't drain totally overnight and do the next fuse the next day. Keep records so you can be methodical about the process.

 

[Gump2773]

Ya.. I need to fill out my profile.. thats my bad. I have an 02 TB LS. As far as the hvac blower I have no clue how to test.

More Information:

I had the headliner out just before this started and installed sound proofing. The only electrical up there was dome light wiring which was put back in same spot and taped down. All lights come on and shut off when supposed to.
Since day 1 of getting the vehicle and installing new HU The gmos adapter I installed clicks every 30 sec or so when vehicle is shut off. I can hear it and have always thought that to be strange.
Im running a 1200 watt amplifier. All shuts down when the vehicle shuts off.

May have to bite the bullet and pay the $85/hour labor cost

 

[The_Roadie]

Just started happening...

Really?

More Information:...

How can I tactfully say this: If you were paying somebody to fix it, you'd probably think to share all relevant information when you discussed the issues with the technician. Just because forum volunteers are free doesn't imply we don't deserve the benefit of having all the same historical and configuration information.

Sounds like your GMOS is bad. It should NOT do that. Pull it, and/or pull the fuse on the amp.

Now I know why a lot of dealers won't work on electrical problems when they see aftermarket stuff, until the vehicle is restored to factory configuration.

 

[Gump2773]

I am giving every bit of information I can think of that may be causing issues. The inline fuse for the amp is disconnected, and the same for all aftermarket audio as well. Im not sure what other information i need to give.

 

[Mooseman]

I had a GMOS 04 go bad on me when I replaced my alternator. It wasn't sending the power signal to the BOSE amp and it wouldn't let the HU turn off so it had to be turned off manually. once I replaced it, all was good again.

Really?

How can I tactfully say this: If you were paying somebody to fix it, you'd probably think to share all relevant information when you discussed the issues with the technician. Just because forum volunteers are free doesn't imply we don't deserve the benefit of having all the same historical and configuration information.

Sounds like your GMOS is bad. It should NOT do that. Pull it, and/or pull the fuse on the amp.

Now I know why a lot of dealers won't work on electrical problems when they see aftermarket stuff, until the vehicle is restored to factory configuration.

Don't take it personally. You would have to have known the "old" Roadie. This is actually pretty tame

 

[Gump2773]

I take nothing personal here, no worries.

My level of frustration is through the roof however. I get that way when I realize I cant control certain situations. Automobile repair has never been a strong suit for me. I think I have covered just about everything I can to my ability. Just so happens this is such a bad time of year to have issues like this. SO many commitments this summer and it seems I have to be so many places at once. I dont have the opportunity for the slow fix because i need the vehicle for travel. So after the upcoming wednesday mechanic appointment if I am no closer to any solution Ill be on the blocks looking for another TB.

:banghead::banghead:

 

[MAY03LT]

I went through the service manual and they don't have a cut and dry draw spec. They say that the maximum allowable draw is 30mA but the typical draw is 7-12mA. In the draw test, they want you to hook up some fancy tool and then use a tech2 to force the bcm to go to sleep before recording the draw.

I would do the draw test again with the mega fuse removed.

Another thing that came to mind, if you opened the rear door to test the fuses in the rear block, the bcm might have woke up. I usually open the doors and rotate the latches closed so the bcm thinks that all the doors are closed.

Also your 02 should have an underhood light, unplug that thing.

 

[Gump2773]

Underhood light was the first thing pulled. Im just gonna let the mechanic have a shot at finding the draw. Now I just need to figure out the fan clutch. When I run the AC I could swear the TB is gonna take flight. Its so loud, I step on the gas at a stoplight and people just stare, and not for a good reason.

Note on the battery draw. When running the air and sitting idle, I hit my front windows to roll em up and the volt meter takes a huge dip. I still think there is alternator issues as well.

 

[Bub]

I have to agree on GMOS I just had this and onstar was activated. My truck the radio didn't work but my brothers it did work. Unplug the module under the rear seat and order a new one

 

[Mooseman]

Does the alternator also take a dip like that for no apparent reason? I had that happen to me with the original and two NEW chinese crap alternators that eventually died. Wound up getting a new Remy alternator from Advance Auto. Good price and lifetime warranty. After about 4 months and running efans, holding up very well even though it too is made in China (probably using teenage instead of child labour )

For the fan, you should repost that issue under a new thread for better responses. I doubt it's related to the alternator.

 

[MAY03LT]

Now I just need to figure out the fan clutch.

That deserves its own thread.

edit: mooseman beat me to it

Note on the battery draw. When running the air and sitting idle, I hit my front windows to roll em up and the volt meter takes a huge dip. I still think there is alternator issues as well.

There is a TSB which addresses this. The gist of it is, there is a delay in between the time that a load is applied and the time it takes the alt to ramp up its output. This delay is what causes the lights to dim and gauge to drop. Now, if the lights are flickering at idle/no load applied, like mine did, I would have the diodes of the alt tested. This can be done with a lab scope or a fancy electrical tester like a VAT 45.

Another note, the GMOS gets its power feed from the same circuit as the radio. So, even if the GMOS B+ driver was stuck/sticking, puling the radio fuse would bring the draw down.

 

[Bub]

That deserves its own thread.

edit: mooseman beat me to it



There is a TSB which addresses this. The gist of it is, there is a delay in between the time that a load is applied and the time it takes the alt to ramp up its output. This delay is what causes the lights to dim and gauge to drop. Now, if the lights are flickering at idle/no load applied, like mine did, I would have the diodes of the alt tested. This can be done with a lab scope or a fancy electrical tester like a VAT 45.

Another note, the GMOS gets its power feed from the same circuit as the radio. So, even if the GMOS B+ driver was stuck/sticking, puling the radio fuse would bring the draw down.

If the radio is pulled does that mean onstar cannot activate at all?

 

[Denali n DOO]

If the radio is pulled does that mean onstar cannot activate at all?

I believe OnStar uses a VCIM not sure if thats the same as GMOS. The VCIM in my Envoy is what was draining the battery.

 

[Gump2773]

Problem solved. Bad gmos, which actually wasnt even a gmos. Was a scosche GMLAN2SR. Pulled it and the draw went to .01amp

Thank you all for your assistance. Now I feel like an ass for not yanking this sooner. Time to get a gmos or just bypass and rewire.