Battery Draw on a 2003 GMC Envoy

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#1
I have a 2003 GMC Envoy. The battery will go dead overnight. I have pulled the under hood fuses and checekd the draw with an amp meter and have found that the blower fuse has a 3.6 amp draw. I see that there is a TSB for the Automatic Dual Zone HVAC. Bulletin Number: 20139007. Has anyone experienced a similar problem and if so how have you resolved it?

Thanks,
CaptainBill
 
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#2
That refers to letting it go to sleep before checking battery draw.....Jim............

This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 02-01-39-007 (Section 01 - HVAC).

When diagnosing battery draws on trucks equipped with the automatic dual zone HVAC controls (RPO CJ2), technicians should keep in mind that the control head does not completely "go to sleep" until after 150-250 minutes, or up to 4-1/4 hours, from when the ignition key is turned OFF. This is a normal condition. In these cases, DO NOT replace the control head.
 
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#5
There are a lot of modules on your car that have to go to "sleep" before checking battery draw on them...I think in one of the other posts on here Transman said GM vehicles take 50 minutes to go to "sleep"...Make sure you don't open the doors or the hood after letting it go to sleep...Jim
 
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#6
I just checked it and the Heater Control must have went to "sleep" but the ABS fuse under the hood still has the 3.5 amp draw. Any Ideas on what may be causing this?

Thanks, Bill
 
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#7
Doesn't solve your battery overnight drain problem, very common cause, like 3 million per year is the voltage regulator in the alternator where the field transistor shorts out. Can put in an ammeter in series with the B+ lead or feel it after the engine cools down. The alternator will still be hot. Some GM vehicles did run the blower motor for about ten minutes to dry off the evaporator, I prefer doing that manually. Parking the vehicle in a dark place helps you find any light bulbs still ignited. Way too much always hot for convenience, but not very convenient if you cannot start your vehicle in the morning.
 

Gus

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#8
Four hours? Any documentation on that?

The longest I've seen modules stay awake is about twenty minutes....first time I ran into this was with a Park Ave., thought I had a draw at around 3 to 4 amps.....as time passed, and more and more modules went to sleep, it eventually got down to 25 milliamps......this was about 10-15 minutes.....

The old cars, you would just install a test light, short it out for a minute...if the light came on when you removed the short, you had a draw....with the new cars and all those modules, you should use an ampmeter...
 
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#9
The alternator is ice cold so I think that will rule out the voltage regulator, the alternator was changed about 6 months ago with a factory replacement. Does anyone have a schematic for the under hood fuse box? So I may be able to track down where the ABS fuse is getting the draw from. Thanks for all the help so far!!

Bill
 

ironhead

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#11
Climb under the truck and put your hand on the motor for the ABS modulator. If you can feel it running, you most likely need a new ABS control module. There is a relay built into the module that powers the pump, sometimes they get stuck on. Before you ask, No, you cannot just replace the relay, you need to replace the control module.
Guy
 
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#12
Thanks for your assistance. I will check it when I get home. I was guessing that might be the issue.

Thanks again, Bill
 
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#13
Hall effect inductive pickup ammeters are nice for this kind of troubleshooting, many available now for under a hundred bucks. Make sure it reads DC with a low range. Yet another problem with always hot is moisture, can be a water leak someplace dripping a couple of drops on a module.

Should do a capacity test on your battery, normally have 2-3 three complete discharges you lose about 80% of your capacity, not good if your alternator should fail in the middle of nowhere.

I get so excited, when I switch off the ignition and put the keys in my pocket, the radio still plays, but suppose to stop when I open the door, but then the interior lights stay on for a half a day when nobody is even in the car. I stand there like an idiot waiting for them to go off hoping they won't discharge the battery. This must be what we want in our new vehicles, I guess. How is this for an idea, turn everything off with the switch, so your vehicle starts the next time you need to use it?
 
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#14
Well..............Quite a few hours later and with some help form a mechanic friend of mine, I am a little closer to finding the Problem. He suggested pulling the Negative Cable and running a test light between the battery and the cable end. With this "tester" in place the test light will stay lit until the fuse with the problem circuit is pulled. An hour or two later I have found that in order for the light to completely go out I needed to pull 8 fuses. Some of which I attribute to the battery "sleep" functions on this vehicle. The problem being that I cannot check all the fuses with the door closed as one of the main fuse panels is beneath the drivers side rear seat.

The fuses I had to pull are as follows; under hood panel, fuse#24 IPC/DIC 10a, fuse#31 TBC 10a, and rear fuse panel, fuse#10 DDM 10a, fuse#12 PDM 10a, fuse#06 LGM/DSM 10a, fuse#36 HVAC 10a, fuse#41 Radio 15a, and fuse#27 OH BATT ON STAR 10a.

If anyone knows of a problem area that I should start with I would greatly appreciate it.

Thanks for all the help so far!! Bill
 
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#15
Did you ever solve your problem? My bother in law has the same problem with a 2001 Envoy. We've isolated it to the DDM and PDM circuit. I'm not sure what they have in common though.