Parasitic Drain 2004 Tahoe -- Help!

[scrnchr]

2004 Tahoe LS 4WD

Hello,

Tahoe sat outside in the rain for a couple of nights and the battery was stone dead. Nothing was left on.

I swapped out the 0.00V stone dead battery for a charged battery. I left one cable off and used a multimeter set to 10 Amps DC to close the circuit as needed for testing.

First try with ignition off, it pulled 10+ amps current. I assume it was recharing some capacitors?

We pulled a few fuses and read 3.6V. Put them in one by one, and it stayed at 3.6V. So the 10+ amps was a one time thing. But still far too high, obviously.

Removing the LBEC 1 (50 Amp) fuse drops the drain from 3.6A to 1.6A. Left that one out.

Removing the IPC/DIC (10 Amp) fuse drops the drain from 1.6A to 1.1A. Still too high! Left that one out.

We removed EVERY other fuse--under hood panel, driver door dash side panel, drive left foot kick panel--the current never dropped below 1.1A.

Checked the wires feeding that kick panel, inspected the insulation, wiggled them... no change.

Unplugged the one car phone charger, so nothing in the front or rear cig plugs... no change.

Checked the trailer plug wiring, it's fine (shouldn't matter, all those fuses got pulled at one point or another).

What is going on here?

And what do those two fuse circuits do? I read the details on the LBEC but having pulled the other fuses am not having any light bulbs appear over my thick skull.

Thanks in advance.

 

[rockenthebowtie]

You might want to let the modules go into sleep mode meaning key out of ignition all doors closed disconnect the negative side of the battery and put your multi-meter in series the negative cable from the meter on the negative battery cable and the positive cable of the meter on the negative side of the battery then you need to wait about 8 to 10 minutes for it to go into sleep mode then check your readings .. anything higher then 50 milliamps is to high.. if so then start pulling fuses..

 

[scrnchr]

Thanks for the reply. I've found a couple of things that go into further detail.

Bulletin No.: 02-01-39-007B, which includes my 2004 Tahoe (though I don't have the automatic dual zone HVAC controls), says it can up to 4-1/4 hours for some systems to go into sleep mode, and to wait at least 5 hours with the ammeter in place, doors closed, key off, before reading the "final" parasitic draw.

I will try that over the next few days.


Bulletin No. 02066 (further down the same page linked above) states: "An anomaly in the operation of the steering wheel position sensor may keep the Body Control Module (BCM) from shutting down when the key is in the "OFF" position. The resultant 3.5 amp draw/load on the battery could possibly discharge the battery to the point where the battery will not have sufficient amperage to start the vehicle."

That "3.5 amp draw/load" jumps out at me, because I am measuring a 3.6 amp draw.

I will leave the LBEC 1 (50 Amp) and IPC/DIC (10 Amp) fuses in, get the ammeter wired into the negative battery cable connection, give it 5 hours for everything to go to sleep, and see what draw I have.

If I still see about 3.5 amps, then it begins to sound like my BCM is not shutting down, the same problem as the 2003 model recalls--but my 2004 does not have such a recall. GM's solution for the 2003's was, "Dealers are to reprogram the BCM." If I would have to go that route, I suppose the stealership will hit me for about a grand for diagnosis, shop time and a new BCM (my warranty is long expired).

Is it possible to reprogram these things outside of a dealership, or has anyone bought one from an auto parts store or online (ebay, etc.)?

Thanks.

 

[rockenthebowtie]

Im doubting either are your problem the the dual HVAC system is a normal characteristic
This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 02-01-39-007A (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 4-¼ hours, from when the ignition key is turned OFF. This is a normal condition. In these cases, DO NOT replace the control head....

The other is to reprogram the BCM on 2003 built in 2 different locations and with a list of the last 8 of the vin #

Year Division Model Plant From Arlington 3R100009 thru 3R181251 and Janesville 3J100001 thru 3J179899
2003 Chevrolet Tahoe

You might want look elsewhere for the draw,, if you have any aftermarket accessories you might want to start there

 

[scrnchr]

Yes, I wrote, "I don't have the automatic dual zone HVAC controls", but I think I was confused... I have the dual slides for heat--I thought by "automatic" they meant the type where you set a specific temperature, like 70 degF (if Tahoes even come with that).

So you're saying the 2003 BCM problem shouldn't apply to my 2004, right? My last 8 digits of the VIN start with "4J", so a 2004 from Janesville, I guess.

The "control head does not completely “go to sleep†until after 150-250 minutes, or up to 4-¼ hours"... so you agree I should try leaving the multimeter between the negative cable and battery for 5 hours and then check draw?

There are no aftermarket accessories at all. Nothing is plugged into the front or rear cig lighter ports.

One thing about the HVAC controls... for many years now the actuators under the dash "hunt"--they go "click click click", and I have to slide the heat controls up or down repeatedly until I find a spot where the "hunting" is quieter. I've tried looking at the actuators and tried one or two "recalibration" procedures but nothing worked. Of course, they don't click at all when the key is off.

Also, just this winter the heat started fading between warm and cold. I figure I'll be replacing the air mix actuator pretty soon, if that's the most likely culprit. I need to check for codes (they've all been cleared lately with the battery stone dead).

I suppose I should disconnect the alternator to check for bad diodes? Not sure how that relates to the LBEC 1 (50 Amp) and IPC/DIC (10 Amp) fuses changing the amp draw.

Should we pull each relay one at a time? We did all the fuses, but not all the relays.

This is a very frustrating problem. I've read forum posts of owners being charged more than $1,000 for the dealership troubleshooting and then fixing these symptoms.

 

[scrnchr]

Went out to set up for the 5 hour test. After just driving the truck, I had to disconnect the negative battery cable to set up the test. With all the fuses back in, I'm seeing 1.5 Amp draw (at the beginning of the 5 hour test), whereas the other day I saw 3.6 Amp. I have no idea why it's different now.

I will check the draw in 5 hours.

 

[scrnchr]

Pretty difficult to do, but I think we might have gotten a valid reading. I had the negative cable tied to the battery negative through a jumper cable. This way I was able to touch the ammeter to insert it into the circuit, then remove the jumper cable from the battery, so that I didn't have to leave the multimeter in series for 5 hours (I wasn't sure if a few amps for that long would be a problem for it--for example, it's rated for 10 Amps for 15 seconds max, then cool off for 15 minutes).

Anyway, I had the multimeter on the 10 Amp scale, because I had been seeing 1, 3, up to 10 Amps in the last few days. When I put it in series, I read 0.00 Amps. That doesn't make much sense, because that means less than .009 or .005 Amps, that is, 9 or 5 mA, when it should be 30 to 50 mA based on what I've read. So either everything went to sleep and the meter doesn't read low currents accurately on the 10 Amp scale, or I screwed up and didn't have a very good connection.

So then I pulled the meter probe away for one second and then retouched it--the current climbed quickly back to 1.5 Amp, like systems woke up due to breaking the circuit and then re-establishing it (battery removed and then back in). Or maybe I just didn't have good contact the first time, not sure.

I'm running out of ideas on this. I thought about checking each fuse for mV drop across the little metal tabs on the fuse top, but since we've pulled every fuse while watching current, I don't think I'll learn anything new.

I've got the spare battery installed now. I recharged the stone dead one (probably junk now) and have it in the back of the Tahoe, just in case. (My jumper box is in the trunk of my daughter's car off at college.)

The truck usually starts if it doesn't sit more than two days. We'll see.

What a horseschmitt design.

Any ideas?

Thanks.

 

[Mayhem]

Any aftermarket things (electronic) installed? If so have they been checked?

 

[scrnchr]

Hello Mayhem,

There are no aftermarket accessories at all. Nothing is plugged into the front or rear cig lighter ports.

 

[rockenthebowtie]

Im not sure if your hooking up your amp meter right it should constantly be in series the 10 amp 15 seconds means that if the amp meter is in a series circuit and the reading is a constant 10 amps for 15 seconds or more.. I've never ever seeing that in my 25 years plus experience of vehicles electrical diagnosis so I'm thinking its not the car make sure that it stays in series when testing even if you turn off the meter most meters will keep the circuit closed with the meter off.. so once you turn the meter back on it will not start the wake up and sleep mode all over again

 

[scrnchr]

Thanks for the reply. It's been cold & rainy here so I haven't gotten as much done outside as I would like.

The Tahoe was starting for more than a week as long as I used it each day. Two days ago, I drove it during the day, parked it at 4 pm, and the battery was dead at 9 pm. I swapped in the spare, fully charged battery and drove the truck, parked it after midnight--dead the next morning.

Today we put the ammeter in series with a charged battery. The truck was drawing 9.8 Amps. Checked a few connections, got a small spark grounding the meter to the alternator housing, and the draw dropped to 3.5 Amps.

Removed all electrical connections to the alternator... no change.

Removed the LBEC 1 (50 Amp) fuse -- drain dropped from 3.5A to 1.5A. Left that one out.

In the underhood fuse block, pulled all relays and all of the large fuses... no change.

I realize this was not the 5 hour test, but hopefully there is some useful info here.

 

[rockenthebowtie]

For the most part you really don't have to leave it for 5 hours trust me on this... not to sound like a know it all or whatever but like I mentioned I have 25 years plus under my belt Chevy and electrical being my specialty... for the most parts 20 minutes is good enough for it to go into sleep mode... check all your interior lighting see if any of them arnt working is so remove the bulb that is out from the socket.. if nothing there with amp meter disconnected open driver door and with a screw driver latch the latch on driver so that the BCM thinks the door is closed the interior lamp switch is integrated into the latch... remove the I/P fuse block cover and start pulling fuses there and see if you find anything

 

[scrnchr]

Thanks for the reply. Had to work around all the rain we've been having.

You were right about the time to sleep mode--turned out to be less than 10 minutes once I found the real problem.

I read through this thread and sort of combined it with your advice. I got a battery disconnect switch (for my side-mount cable) and added a couple of small screws to clip my multimeter leads to. This made it really easy to leave the battery in the circuit and check the drain whenever I wanted to, by turning on the multimeter in the correct Amps mode and then using the switch to disconnect the negative cable from the battery (the meter leads bridge the disconnect switch).

I again found about 9.8 Amps flowing. That is so large...

But I had found free wiring diagrams here, and I was able to see which I/P fuses (on the drivers side inside panel) were coming from which underhood fuses--that helped a lot. One of the downstream fuses was for the driver electric seat controls. And guess what--over the years the screws holding the trim on the left side of the driver seat had loosened (most had fallen out), and sometimes the trim would shift enough so that when the door was closed, the hard plastic "pocket" molded into the bottom of the door would engage the switch in the "front down" position--that was my 9+ Amps draw. At some point, this would apparently "cut out", but it seemed to keep other systems awake for a long time.

I found the part number for the black screws for the trim--GM sets a price of $10.10 per screw. Typical. I found better screws at a hardware store for 33 cents each. Got the trim back in place and the 9+ Amp drain is gone. At first, the drain is 3.6 Amps, then the dome lights fade out and the drain drops to 1.5 Amps. Within 10 minutes, the systems go to sleep and the drain is a steady .0156 Amp, i.e. 15.6 milliAmps (mA), well under the 35 to 50 mA "normal" threshold (no OnStar, thank you very much). The truck has been starting faithfully for almost a week now.

So it was my stupidity to not replace the driver seat trim screws as each one fell out. Dumb.

Thanks for the help!

 

[rockenthebowtie]

De nada.. Sweet glad you got it figured out... its people like you that keep me here to help out you are one of the few that at least has the decency to return and post your findings and a kind Thank you that some here you never hear from again and don't understand how far those 2 little words can mean so much.. Was a great pleasure to help you out bro.. Take care : )