SOLVED! Parasitic Draw

Mooseman · Sep 23, 2020

So the Saab has cost me a few bucks with a new alternator and battery and it keeps dying in a week or so. So I've got a parasitic draw. Using the multimeter to measure amps, I'm getting a 1.27A draw. Quickly found that my ScanGauge II left plugged into the OBD port would draw over 1.1A and it would constantly keep coming on by itself for no reason. So that's resolved by just unplugging it when not using it.

So now I'm left with 0.18A still drawing. The Takonsha trailer brake controller is constantly drawing just .01A. The Android radio I didn't see a drop when I pulled its fuse but it did wake up and draw a bit when I put the fuse back in and it eventually went back to sleep. It was getting dark and called it for tonight.

Is 0.18A draw at rest too much? Anybody else know how much these trucks draw at rest?

freddyboy61 · Sep 23, 2020

180mA sounds kind of reasonable. Is this after all the modules have gone to "sleep"?

BrianF · Sep 23, 2020

I cannot remember what mine had but that 18 might be close to the money. Now the hell if I would remember to check mine to help...

mrrsm · Sep 23, 2020

If the SAAB Battery Ground Cable has a Sketchy Chassis Connection… ALL of the Modules that employ Hibernation Features might be re-setting themselves again and again and causing this drain.

The remedy is to remove and replace the Ground Cable if there are ANY Signs of Green Corrosion on the Connectors or penetrating inside of the Cable Copper Bundles underneath the Insulation.

Also... A Bad Diode in the Alternator Voltage Rectifier Circuit can caus the SUV Battery to Drain Down.

The Vehicle Battery also needs to be taken off-line and tested independently and likewise, charged independently and re-checked. If the Battery Voltage drops below 10.5 Volts… it may have become unreliable.

As for whether or not the Ah Draw is within limits… the following calculation breakdown might help to work things out against whatever the factory recommends as an acceptable loss in Amperage. Here is the Formula being used in an Amperage-Hour Draw Down Problem:

Q = I * T

Q = The Amount of Energy measured in Amps/Hours (Ah).
I = The Current Flow (Amps).
T = The Time Period the Draw- Down is Active.

Using a Three Day Period as a Baseline (72 Hours) on a 60 Ah Standard Battery...

I * T = Q

0.18 X 72 = 12.96 Ah

So ...over the 3 Day Period… The Total Loss in Amps would be 21.6 % of a 60 Ah Standard Battery.

THIS VOP has some interesting ways to run the Parasitic Drains to Ground with and removing the Positive Battery Terminal in ways that will NOT cause your System Settings to be Lost:

Reprise · Sep 24, 2020

From what I can see, that kind of draw is likely on the 'high side of normal'.

Found a TSB concerning the key-off draw of the electronic HVAC ctrl head (apparently, it can take 'hours' to go to sleep, and GM considered it normal):

Bulletin No.: 02-01-39-007B
Date: November 05, 2007
INFORMATION
Subject:
Automatic Dual Zone HVAC Battery Draw
Models:
2004-2007 Buick Rainier
2003-2008 Cadillac Escalade Models
2002-2008 Chevrolet TrailBlazer
2003-2008 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2002-2008 GMC Envoy Models
2003-2008 GMC Sierra, Yukon Models
2002-2004 Oldsmobile Bravada
2003-2008 HUMMER H2, H3
2005-2008 Saab 9-7X
Supercede:
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 4-1/4 hours, from when the ignition key is turned OFF. This is a normal condition. In these cases, DO NOT replace the control head.

Where I found this page (the vehicle in question is an '04 TB, although I wasn't searching for a 360, specifically):

What is normal parasitic current drain?

This is Dave again. The question is now answered and the problem has been solved, so I’m posting this for those who might benefit in the future. I’ll tell you (1)what I believe the correct answer to the question to be, (2) how the problem was resolved, and (3) what I learned about...

community.cartalk.com

(the above link should take you directly to the solution(s) found - it's the '14' reference at the end of the URL). Looks like the 'big' one had to do with the dome override switch being on, which kept the interior courtesy lamps off, but his interior lamp switch was 'on', and at full brightness - which, while the lamps weren't visibly 'on', voltage was being commanded via the lamp switch.

A few posts earlier (#11), the 'official' Alldata test procedure was given. It utilizes a J-tool, and the only reason I even mention is is to show the complexity of the procedure.

Hopefully, one or more of those will help w/ your problem (and you don't have to resort to the test procedure above).

Mooseman · Sep 24, 2020

Thanks gentlemen. Some answers I can provide.

@freddyboy61 , Yes, that was after about 15-20 minutes of just waiting and the readings didn't change. However, I may have missed one of the door locks when closing the latch to simulate all doors closed so I might have to redo my tests.

@MRRSM , Alternator and battery are new so I doubt very much those are the cause. Although I haven't looked at the grounds, everything is working correctly except for the aftermarket ScanGauge II which I will be leaving disconnected when not in use or I may figure out some way of automatically cutting power to it as I do like it. The method the VOP gives is interesting however not usable with our side post batteries and I have already lost my radio settings :frown:

@Reprise , wish that TSB gave a definitive number of normal draw but that post did give 25-35mA as normal. I do remember pulling the HVAC-B fuse and it did nothing to change draw. I would try to compare to the TB however my son has been using it as his daily ride lately and hard to pin it down.

So plan for today, starting earlier during daylight, is to hook up my DMM for current draw in the mA range, ensure all the door locks are latched and waiting a couple of hours for everything to go completely to sleep. Depending on reading, I will redo the fuse pull method to see what is drawing. I will disconnect the brake controller just to eliminate that draw.

budwich · Sep 24, 2020

you might consider "gross disconnecting" as a means to focus the search.... although it might take out more than you want. Gross-> disconnect the rear fuse box from the engine box and check the result... go from there.

Your "~.2" amp is pretty high for a long term drain.

mrrsm · Sep 24, 2020

For the 2nd time in recent history... I'm going to go out on a limb and risk having to "Eat My Own Words"...perhaps a more nutritious meal than should be allowed .... and imagine that the Prime Suspect in the Current Drain Problem will emerge as some portion of the SUV LGM not doing its job and pulling power "after dark" as the result of a short inside of it ..or in the Lift Gate Conduit Wiring ...even if the Physical Latch is Secure after being closed correctly.

Expeditor · Sep 24, 2020

Here is a good video that explains the good, bad and the ugly of the different ways to test for parasitic loads. Of course everyone has his or hers favorite ways for personal reasons. The video shows why, how and why not to use certain test. Hope this helps.

Mooseman · Sep 24, 2020

Solved! And the winner is.... front seats! Or more specifically, the passenger seat. Still getting the .16A draw. Start pulling more fuses and get to the 30A breaker for the seats and voilà, drops to .01-.02A. Put the breaker back in, I could hear a passenger seat motor clicking on. The switch was stuck in the down position so after a while the motor/module would stop it, it still drew .15A. Confirmed after everything goes to sleep, it's drawing between .01-.02A (my DMM is weird where I can't get actual mA, all it does is move the decimal but numbers stay the same). Switch was fine, it was just jammed in the plastic.

I probably would have found it yesterday if I had more time.

Thanks all for your input.

linneje · Sep 24, 2020

Yup, I had the exact same problem (but on the driver's side). Jammed the plastic part of the switch to keep the draw of current on.

Robin B · Sep 25, 2020

Mooseman said:
Solved! And the winner is.... front seats! Or more specifically, the passenger seat. Still getting the .16A draw. Start pulling more fuses and get to the 30A breaker for the seats and voilà, drops to .01-.02A. Put the breaker back in, I could hear a passenger seat motor clicking on. The switch was stuck in the down position so after a while the motor/module would stop it, it still drew .15A. Confirmed after everything goes to sleep, it's drawing between .01-.02A (my DMM is weird where I can't get actual mA, all it does is move the decimal but numbers stay the same). Switch was fine, it was just jammed in the plastic.

I probably would have found it yesterday if I had more time.

Thanks all for your input.

Same problem on the Drivers Seat. it's now down to .018-.02a.

mrrsm · Jul 23, 2022

I saw this information mentioned and provided by @Mooseman in another Thread and decided from this Good Sense Suggestion to invest in getting:

A QuickLynx Blue Tooth 4.0 Battery Monitor II Unit:

THIS is How It Hooks Up and Works: