2013 Chevy Tahoe Z71 PPV Outfitted, Battery drains overnight.

[kylebnoris]

Back at it again, this time with a GMT900!

I have a buddy that owns a 2013 Z71 Tahoe 4x4, it is pretty much loaded. It was however outfitted as a PPV vehicle. He is the 2nd owner.

I appears to have the whole 9 besides the rear seat delete for suspect containment. However it has a partial console install. All the lights retain their flash ability with the control module removed but it seems all blue and red interior and exterior lights have been removed.

Now they have owned the truck for about 3 years, and drive it about once a week.

Recently they have had the battery start dying overnight. No obvious issues, all interior and exterior lights appear to sleep, a long with the cluster and radio. I did a parasitic draw test via a multimeter online with the negative battery cable.

KOEO, at about 110.00 mA then as I pulled fuses from the under hood fuse box and the dashboard driver fuse box. Never saw a drop from an individual fuse however over about and hour of troubleshooting it dropped to about a steady 49.3 mA

Initially it would start at 110 then slowly drop to about 60-55 then after an hour of pulling fuses it would hold at about 49 only spiking when I reconnected the leads or had to turn the multimeter back on.

I have not yet pulled fuses from the driver side foot well area as I ran out of time.

They have complained of the back glass randomly popping itself open going down the road and did notice a rodent issue also in the back cargo area that was solved with traps. Those two issues didn't immediately cause the battery draw but were prior to this issue.

Any ideas? I'm still learning electrical so please bare with me.

 

[RichardCranium]

From previous years where I turned wrenches for a living, and from a couple of key parts you pointed out, the first thing that pops in my head is going to be the idea you don't want to hear. That is going to be chewed wires. You've done the best rule of thumb though with the K.I.S.S. method, putting the truck to sleep and pulling fuses with a multimeter to watch amperage draw. I can't recall what fuses are in the drivers side of the dash, but imagine they are body/interior related, so imagine you might solve your parasitic draw, or at least isolate it from there.

I'd pull the D-pillar trim and the cargo panels and find the nest. I'd bet you are going to find a nest/bedding area with carpet and even some wiring tape. Usually those mice will scavenge from the same place, so hope its all pretty obvious when you do locate it. I'd bet you're gonna find your draw and your mystery hatch-popping together. I know the tailgate/hatch harness is fed from the top, worse case scenario you might need to pull the headliner if you have evidence those little MF'ers made it up there.

 

[mikez71]

If a dual battery setup, often a dying battery will be pulling the other one down with it..

 

[Sparksalot]

If a dual battery setup, often a dying battery will be pulling the other one down with it..

One of my PPVs did that.

 

[Doubeleive]

also check the wire harness that feeds into the rear hatch from the body that is visible top center when you have the rear hatch open
look for any wear, bare wire.

 

[kylebnoris]

From previous years where I turned wrenches for a living, and from a couple of key parts you pointed out, the first thing that pops in my head is going to be the idea you don't want to hear. That is going to be chewed wires. You've done the best rule of thumb though with the K.I.S.S. method, putting the truck to sleep and pulling fuses with a multimeter to watch amperage draw. I can't recall what fuses are in the drivers side of the dash, but imagine they are body/interior related, so imagine you might solve your parasitic draw, or at least isolate it from there.

I'd pull the D-pillar trim and the cargo panels and find the nest. I'd bet you are going to find a nest/bedding area with carpet and even some wiring tape. Usually those mice will scavenge from the same place, so hope its all pretty obvious when you do locate it. I'd bet you're gonna find your draw and your mystery hatch-popping together. I know the tailgate/hatch harness is fed from the top, worse case scenario you might need to pull the headliner if you have evidence those little MF'ers made it up there.

Thanks for the response,

We did do a amperage draw test while the vehicle was off, I posted that above in the post but maybe I didn't explain well. In summary It was about 110.0 and slowly dropped to about 49.3 throughout the whole process. However we never saw a drastic change or difference. We worked our way through the entire fuse box under the hood and the driver side dash board interior box. There is a third box next to the brake pedal that we haven't pulled from yet.

I'm assuming the draw is less than 49.0 and we didn't locate it?

 

[kylebnoris]

If a dual battery setup, often a dying battery will be pulling the other one down with it..

lack of the 2nd battery in what appears to be a battery location on the driver side by the front apron seems it may have had one at one time but It doesn't any longer. I'll double check for the wiring but I didn't immediately notice any disconnected battery cables in the vicinity. The main battery is located on the passenger side right against the firewall

 

[kylebnoris]

Bump.

 

[mikez71]

Is the battery more than 3 years old as well? Could it be a dying battery?
The current draw numbers you show seem to be in the acceptable range?...

 

[Fless]

Instead of pulling fuses, have you tried measuring the voltage drop across the fuse test points (at least the ones you can)? That might help pinpoint what circuit is still awake. Plenty of YouTube videos on this method.

Depending on what aftermarket equipment is installed, the fully-asleep draw should be no higher than 50 mA, but 20-30 mA is more like the norm on a stock system. If it has an aftermarket alarm system, etc., YMMV.

 

[kylebnoris]

Is the battery more than 3 years old as well? Could it be a dying battery?
The current draw numbers you show seem to be in the acceptable range?...

Battery was replaced in January, 12.3 was my reading but this is not after a charge. It was when I showed up on site. Guy said the battery charged and tested fine at the local parts store prior.

 

[kylebnoris]

Instead of pulling fuses, have you tried measuring the voltage drop across the fuse test points (at least the ones you can)? That might help pinpoint what circuit is still awake. Plenty of YouTube videos on this method.

Depending on what aftermarket equipment is installed, the fully-asleep draw should be no higher than 50 mA, but 20-30 mA is more like the norm on a stock system. If it has an aftermarket alarm system, etc., YMMV.

Yeah so it was pulling 110mA immediately when connecting leads but slowly drops to about 60 then eventually through out pulling fuses (to hopefully see an immediate difference in draw and pinpoint AT LEAST the affected system/circuit)

It eventually settles in between 49-48mA

KOEO of course.

 

[mikez71]

12.3V seems good?

You could try disconnecting the BCM fuse and see if the draw is 60mA right away..
(just to verify that the 110mA is retained accessory power)

If 50mA is acceptable, is a 60mA draw going to drain the battery overnight? (serious question, seems like it shouldn't)

Is it only not starting? or are the lights dim too?

 

[kylebnoris]

12.3V seems good?

You could try disconnecting the BCM fuse and see if the draw is 60mA right away..
(just to verify that the 110mA is retained accessory power)

If 50mA is acceptable, is a 60mA draw going to drain the battery overnight? (serious question, seems like it shouldn't)

Is it only not starting? or are the lights dim too?

The time scale for it to drop is odd, it's immediately 110 then drops down to eventually 49 but it isn't slow enough to watch etc.

It seems to drop steady when the BCM fuse is pulled or if it's installed, so I don't think it it's the BCM. There isn't a immediate difference.

Lights in the interior when it's was at 12.3 were fine. No issues starting.

 

[kylebnoris]

Bump,

Once I localize the issue in a circuit via parasitic draw testing through yanking fuses or disconnecting equipment I'll run a voltage drop test after I make sure it's getting power, and OHm's out right.