Intermittent battery drain - '06

[4WDTRK]

Found my battery dead down to 4v after parking for a few days. I don't drive the truck a lot so it sits for a week or more a lot, but hasn't been an issue until recently.

First thing I did was change the battery. Now working with a fresh battery it happened again. I'm getting 1.1v current draw that comes and goes. I've done some fuse pulling and monitoring and got confused. I believe due to the intermittent nature it's more difficult.

More recently during my testing I found the door lock on the drivers side to stop working when pressing the unlock button. I never noticed this before, and after a few minutes it cleared and is working normally again. I've tried to reproduce this, but it's still working normally making me scratch my head.

I also noticed for a long time now that when I put the truck in park the door locks no longer automatically unlock. I now need to turn the key off and remove it before they will automatically unlock. Why would this change?

Yesterday I parked the truck and left it unlocked (I usually always lock it). A couple hours later I checked for battery draw and it was normal. I grabbed my FOB and locked the doors. After waiting for the systems to go to sleep I'm still seeing 1.1a draw. Then I press unlock on FOB and the draw will go back to normal.

I've read a lot of old threads and it seems to point to the drivers door latch/switch, BEC, PCM connectors, etc., but I'm not really sure what to do next. Again the test results can be inconsistent/intermittent and that throws me for a loop!

TIA for any help!

 

[Fless]

How and where are you measuring the draw? Inline ammeter, or inductive clamp, either one on the negative battery cable?

Any aftermarket electrical add-ons? Alarm system, radio, radar detector, camera, etc.?

Best way to start is to pop the hood and let it go to sleep, then measure the mV across every mini-fuse -- using the integrated test points on the fuse -- to see where current is flowing. Start in the underhood electrical center. Any minifuse that has a mV drop has current flowing on that circuit. There is a conversion chart to convert from mV to estimated mA draw, and I've posted that in other threads. Will update this one when I can, later this evening.

Pulling fuses can wake up modules, so that can be counterproductive.

A couple of things to watch: do your interior lights go on and off consistently when opening and closing the last door?

Does your RAP time out after about 10 minutes if you sit in the truck after shutting it (the truck) off? Leave the radio on sometime, remove the key, and open the door. Does the radio always turn off immediately?

The AUTO HVAC head can take several hours (up to 4 or so) to fully go to sleep. Most snooze earlier than that but be aware.

 

[rockola1971]

All of these modules need a ground reference to operate properly and that includes going to sleep. Ground ( 0 volts) is the reference. If you have a broken, corroded or loose ground you will have all kinds of weird things happening electrically OR just one. First 2 to check are the ground at the rear of the engine which connects to the firewall. Its a flat braided ground strap which typically breaks in half or at the attachment point on the firewall or engine block. They can also get full of green/blue corrosion which changes the resistance of the strap and screws up the purpose of the ground point. Then there is the another key grounding point on the drivers side chassis directly under your drivers side front door up near where the firewall starts. This point will usually have more than one wire attached. Remove the bolt, wire brush frame and bolt then clean the terminal lugs on each wire and reassemble.
Have also seen bad BCM's just refuse to goto sleep because of a shorted transistor inside them and in that case the BCM has to be replaced and reprogrammed to your vin.

 

[4WDTRK]

Thanks for all the info @Fless !

I'm measuring with an inductive clamp meter on the negative battery cable.

I have an aftermarket head unit (Kenwood).

I've never performed a mV test, I'd like to know more about how to perform that.

Interior light function normally and radio shuts off immediately upon opening the door. Yes RAP is working normally as far as I know, I haven't tested it recently, but it always worked.

I don't have auto HVAC (I assume you mean the digital console controls) so no issue there.

 

[4WDTRK]

All of these modules need a ground reference to operate properly and that includes going to sleep. Ground ( 0 volts) is the reference. If you have a broken, corroded or loose ground you will have all kinds of weird things happening electrically OR just one. First 2 to check are the ground at the rear of the engine which connects to the firewall. Its a flat braided ground strap which typically breaks in half or at the attachment point on the firewall or engine block. They can also get full of green/blue corrosion which changes the resistance of the strap and screws up the purpose of the ground point. Then there is the another key grounding point on the drivers side chassis directly under your drivers side front door up near where the firewall starts. This point will usually have more than one wire attached. Remove the bolt, wire brush frame and bolt then clean the terminal lugs on each wire and reassemble.
Have also seen bad BCM's just refuse to goto sleep because of a shorted transistor inside them and in that case the BCM has to be replaced and reprogrammed to your vin.

Thank you @rockola1971 I'll take a look at these grounds!

 

[Fless]

See this link for some info, a link to the conversion chart, and a link to a helpful video.

EDIT: check the specs on that amp clamp; most of them that measure AC have too large a jaw opening to be accurate at the very low DC levels you're trying to measure. If you get super serious about testing and have a good (secure) place to leave the hood open and use an inline ammeter, just don't try to start it with the ammeter inline.

Also, a thermal camera can show warm/hot spots in the fusebox, too.

Weird current draw

Has anyone ever experienced a parasitic draw that would alternate between .7 and 3.4 amps? I thought I was having connection issues with my meter, but even once I had solid connections the draw would still change. It seemed to change about every 20 seconds or so. I don't know if I'm dealing...

www.tahoeyukonforum.com

 

[4WDTRK]

Ok I've still been poking away at this. Here's what I've found. If I park the truck and lock the doors I see ~1.1 amp draw. If I use the FOB and unlock just the driver's door, the draw will go back to normal. If I use the FOB to lock the doors again the 1.1 amp draw comes back. So this seems to be pointing to an issue with the drivers door.

What can I do next to further pinpoint? Is there a common part here that fails?

It's really a bummer because for the sake of time I took it to my local mechanic that I've trusted for years and they said it's my aftermarket radio (this was before I even started this thread). They determined this by pulling the main radio fuse. However, I've left the fuse out and I still have the issue. Part of me wants to call them back and let them know it's still happening. If I can pinpoint it myself though I may just repair it myself if it's not too involved. Thanks!

 

[rockola1971]

Ok I've still been poking away at this. Here's what I've found. If I park the truck and lock the doors I see ~1.1 amp draw. If I use the FOB and unlock just the driver's door, they draw will go back to normal. If I use the FOB to lock the doors again the 1.1 amp draw comes back. So this seems to be pointing to an issue with the drivers door.

What can I do next to further pinpoint? Is there a common part here that fails?

It's really a bummer because for the sake of time I took it to my local mechanic that I've trusted for years and they said it's my aftermarket radio (this was before I even started this thread). They determined this by pulling the main radio fuse. However, I've left the fuse out and I still have the issue. Part of me wants to call them back and let them know it's still happening. If I can pinpoint it myself though I may just repair it myself if it's not too involved. Thanks!

Sounds like a BCM that aint going to sleep. Its a ground or BCM problem.

The window motors should not ever have any power to them once the last door is closed on the vehicle. Power lock switches Hot all the time. So I would pull the fuse for locks and see if your problem goes away and if it does then there is a good chance that you have a shorted output on the BCM to the power locks lock function output of the BCM. Lock and unlock are 2 different outputs from the BCM IIRC. Ill have to grab up the schematic.

Ive heard of a burnt power lock switch causing this same problem.

 

[Fless]

The BCM ground is on the body mount on the frame rail, under the driver's door hinge. There are two or three critical grounds there; remove, clean, and tighten. Protect with paint or some kind of protectant.

Here's a zoomed diagram of that area; the attached PDF can be expanded for better clarity. (From the GM Upfitter's Guide)

 

[4WDTRK]

Sounds like a BCM that aint going to sleep. Its a ground or BCM problem.

The window motors should not ever have any power to them once the last door is closed on the vehicle. Power lock switches Hot all the time. So I would pull the fuse for locks and see if your problem goes away and if it does then there is a good chance that you have a shorted output on the BCM to the power locks lock function output of the BCM. Lock and unlock are 2 different outputs from the BCM IIRC. Ill have to grab up the schematic.

Ive heard of a burnt power lock switch causing this same problem.

Great info thanks! Is that door lock fuse in the main fuse box under the hood or on the side of the dash?