2004 SUBURBAN PARASITIC BATTERY DRAIN DRAW BCM? Have PICS & VIDEO OF PROBLEM... CANT FIGURE THIS ONE OUT!

[W8MCC]

2004 SUBURBAN Z71

 

I need some help.

 

My suburban sometimes goes dead.  It will go dead every day for a week, and then not again for a month.  Right now, its doing it again.

 

I have:

Replaced the battery (twice) on a new battery < 1 week old.

Had the alternator tested 3 times.

Replaced a questionable looking harness connection on the alternator with a soldered in connector properly heat shrunk.

Replaced the Instrument cluster about 6 months ago with a rebuild due to bad steppers. (not because of battery drain) but I mention it because its popped up before.

Performed numerous parasitic draw tests and found a possible issue:

 

Here's what I have found so far.  My natural battery off state is 0.03A or 30mA.   I have confirmed this with a matching truck I have where it has an off state draw of 22mA.  They're within reason to each other so I consider that the normal state for my vehicle.

 

I have caught what I feel to be the issue twice, where I have a draw of 0.22A or 220mA almost a 1/4 amp and solid.  It doesn't happen every time though.  I only luckily found this twice while testing.  The only way I can get the draw to disappear when it comes up by itself is to pull TBC BATT.  And I only know its happening because I have a meter in line with the battery while testing.

 

I can simulate this same draw by doing the following:

 

1: Wait for the natural off state to settle in around 0.03A.  This takes about a minute, first it starts off at 2.8A, then drops to 1.8, and so on as features are put to sleep after connecting the battery.

2: Pull the LBEC 1 Fuse.  This makes the battery draw jump from the settled state of 30mA up to 190mA.

3: Reinsert LBEC 1 Fuse.  This then jumps the battery draw all the way up to 220mA, which I consider to be the actual problem.  The thing is it never drops back down.  It just sits there indefinitely.

4: (to solve the issue) If I pull TBC BATT that instantly drops the draw back to the normal off state current, and when I reinsert TBC BATT the draw doesn't come back until I repeat the process above.

 

Notes:

A: when this happens, pulling any fuses in the cabin fuse panel does not drop the current.

B: There is an audible click from a relay or something INSIDE the BCM under the dash.  My other truck does this too, but I'm not sure what's on the aft side of that connection.

 

I checked out some of the free wiring diagrams at autozone.  Unfortunately they're not organized too well and I'm getting lost with them, that and once the diagram enters the BCM I'm not sure whats going on with the circuits after that.

 

Anyone here have some insight to what to do?  Like I said before, I have another identical truck (just not Z71) I can swap parts and pieces with to narrow it down.  I will mention that on the other truck, if I do the steps above I get the same result BUT it eventually does settle down to 0.02A by itself where the Z71 does not.  It just draws that 1/4 amp all day long (usually all night long).

 

Here's a video of my test:

 

https://photos.app.goo.gl/SBdFzXxGzgdzuzAR8

 

Here are the two offending circuits in the underhood fuse panel:

 

 

 

[Supreme Pizza]

I have an 03 Burban. It was fine for years. After parking it for a few weeks, the battery went dead. Charged it up and disconnected the battery. Used it once, and disconnected the battery. Used it again and disconnected the battery. Used it again but left the battery connected. After a week the battery was still fine, so I figured it was good to go. A week later, the battery is dead. I beep the alarm daily when the battery is connected, so I can monitor the battery condition.

 

So its on the charger right now. Guess I need to go back to disconnecting the battery.

 

I suppose I could try to track down the intermittent draw, but its not a vehicle that is used regularly, so why bother.

 

What ever your problem turns out to be, I might look at mine to see if its the same issue.

[OldFortBear]

The Solution on my truck:

 

We brought a 2004 Yukon Denali 6.0L Vortec six years ago and had the same problem with the slow parasitic battery drain.  I took me two years of frustration and two batteries to find it.   I pulled fuses, check the meter, pull fuses, check the meter, cuss some more.  It would die every few days if you left it seating with out cranking and running.   It was so frustrating.  Like I said it took me two years to track it down.     It was the dash console.  The gauges in the dash.   I pulled the dash apart and unplugged my dash console and the ohm meter immediately dropped.   I sent the dash console to a guy off Ebay for like $110 buck to rebuild the gauges (sorry I can't remember what he called it, like new motors in them) and put LED lights in it.  I drove the truck for like a week with no gauge console which was hilarious, just remember you have no gas gauge or speedometer! Week later got it back and bingo, never had the battery drain issue again.     It only takes like 10 mins to get the dash apart to check and the truck doesn't need the console to run so its worth a few minutes to check yours.   I hope this helps!  Good Luck!  Now if someone could help me find an oil leak I have been chasing for two days now.... Ugh....    

[Supreme Pizza]

On 1/1/2022 at 5:21 AM, OldFortBear said:

The Solution on my truck:

 

We brought a 2004 Yukon Denali 6.0L Vortec six years ago and had the same problem with the slow parasitic battery drain.  I took me two years of frustration and two batteries to find it.   I pulled fuses, check the meter, pull fuses, check the meter, cuss some more.  It would die every few days if you left it seating with out cranking and running.   It was so frustrating.  Like I said it took me two years to track it down.     It was the dash console.  The gauges in the dash.   I pulled the dash apart and unplugged my dash console and the ohm meter immediately dropped.   I sent the dash console to a guy off Ebay for like $110 buck to rebuild the gauges (sorry I can't remember what he called it, like new motors in them) and put LED lights in it.  I drove the truck for like a week with no gauge console which was hilarious, just remember you have no gas gauge or speedometer! Week later got it back and bingo, never had the battery drain issue again.     It only takes like 10 mins to get the dash apart to check and the truck doesn't need the console to run so its worth a few minutes to check yours.   I hope this helps!  Good Luck!  Now if someone could help me find an oil leak I have been chasing for two days now.... Ugh....    

 

 

 

Someone asked me to replace the rear main, to solve an oil leak issue. I looked it over, and discovered that the rear part of the valve covers was leaking oil down onto the bellhousing, simulating a rear main leak. What is the situation with your leak?

[The Real Virgil]

On 1/2/2022 at 2:32 PM, Supreme Pizza said:

 

Oil sending unit/sensor. 100%

 

Someone asked me to replace the rear main, to solve an oil leak issue. I looked it over, and discovered that the rear part of the valve covers was leaking oil down onto the bellhousing, simulating a rear main leak. What is the situation with your leak?