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Discussion Starter #1 (Edited)
In my 2007 EOS VR6, I finally have isolated my parasitic drain to Fuse F16, which the book says is for the electronic steering column
Once I figured out how to get the car system to settle down and get everything to go to sleep that word, I was able to find this fuse suspect using the mV reading across the contacts on the fuse.
After that I put my Ammeter in series with the disconnected battery terminal and let it sit for quite a while. After multiple hours, I went back and checked the current there was a draw of 110 mA. When I pulled fuse F-16, it went crazy high and then came down within less than a minute. When I took the fuse out the draw went down from 110mA to 10mA.
If my problem actually is coming from something in that circuit, what’s my next step?
 

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My battery drain after 10 minutes is 50mA = about 60 days from a full 80Ah battery and what I I would expect in CAN sleep mode with the alarm and immo active and led flashing?
 

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Discussion Starter #3
My battery drain after 10 minutes is 50mA = about 60 days from a full 80Ah battery and what I I would expect in CAN sleep mode with the alarm and immo active and led flashing?
First, I'm glad to be having this conversation with you after having read so many of your EOS posts in this forum...
Now, a few more questions, especially since I'm not even a mechanic but just a guy with some engineering knowledge and the ability to search YouTube videos.
1. What is immo?
2. If the car has been off for an extended period, say 2-3 hours, and I disconnect my battery cable to insert the MM into the circuit, does that affect the current behavior of any of the electrical system's components (i.e. waking anything up)?
3. When I have the battery fully connected and probe across Fuse 15 (Interior Lighting), it may start as high as 187mV when first connected but immediately comes down to numbers that would not indicate that it could blow my circuit box in my house. However, it still runs at high mV readings of 3-4mV when a 0.1mV reading translates to 370-460mA. I've NEVER measured that kind of draw.
Why would this fuse behave so erratically?
4. The most likely culprit is Fuse F16. Once I've gotten everything to apparently go to sleep, and insert the MM into the loop at the battery, it has read a stable 0.11A and then hovers at 0.01A after pulling F16. Would you agree that this is the damning evidence that my problem is connected to that fuse?
5. If Fuse F16 is the point to start looking deeper, what is the next step?
6. Could this be a problem with bad relays, sleep mode or otherwise? If so, are they the ones in the high-level fuse box under the hood?

Another point of interest:
Last night, batteries were at 12.61V.
This morning prior to starting, at 12.24V
Immediately after starting, at 13.6V (I think - I screwed up and did not record the info and may be misremembering, duh)
After running 10 minutes, at ~14V
Right after turning off, at ~12.4V.
I plan to perform this test again after the car has set for several hours, actually recording the values.
 

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Whilst the Canbus modules should all be put in standby/sleep, there are some active modules. These include the immobiliser and alarm and where most of my 50mA comes from, but I'm happy with that. Testing volts drop across fuses is a handy trick, but there are some car electrics and electronics which are not fused at all e.g the alternator diode stack and charge controller. Trying to convert the mV reading to Amps current is error prone because different value fuses and contact holders have different resistance. Testing that way is only any good to confirm current is being drawn, if you want the real figure you connect the ammeter in series with the fuse. But whenever you do that you have to turn off the ignition and back on.

The interior lights are electronically controlled by a dimmer/timer to turn them off. If you break any circuit to insert a MM in series, as long as you turn off the ignition first then turn it on and then off to watch the current drain, that should be O.K because all the modules should boot correctly then shut down (after 10 Min) when the key is off. If the MM circuit is broken after switching on the ignition, I think this creates an abnormal system condition?

The discharge current you measure in series with the battery tells the truth but I wouldn't agree that pulling a fuse is 'daming evidence' because modules on that circuit may be good but not getting or responding to the CAN shutdown message. Isolating modules with their fuses could interfere with the CAN shutdown process, because messages expected won't get back to confirm they have shut down and other dependent modules may stay alive.

If I put an ammeter in series with the battery leads it takes about 10 minutes for my CAN to go to sleep. From memory the current started at about 180mA then dropped to 50mA, but when I had a bad Chinese cloned Gateway module I got bad battery drain. If you or somebody has uprated the radio and replaced the Gateway module, check that isn't your problem. You will find a lot about the Gateway module causing battery drain problems, but I suspect these are the Chinese clones like the one I tried. Are you sure all the modules are genuine V.W and some haven't been replaced with Chinese clones? If any modules have been replaced as DIY repairs, even V.W genuine, there could be compatibility issues with older modules. If V.W do the work they fit a newer replacement part, check the version status of older modules and reflash or replace any that may be incompatible. Of course they can't do that with Chinese units.

I might use the mV readings across a fuse to confirm current was being drawn, but never to get an accurate measurement of current this small, because results will change with fuse value and contact resistance. The total current measured at the battery (I don't use a Hall D.C clamp for these low currents) should approximate to the sum of current drawn through each fuses plus a small extra for any unfused circuits.

Your alternator is charging because you measured 14V. The only thing that matters is the actual current draw measured in series with a battery lead and the condition of the battery if it is old and self discharging. As a rough guide, if you measured around 100mA self discharge and never used the car, you will get the approximate time to dead battery (well probably work to 30% for sufficient charge to start it). If your self discharge is much faster then either something intermittent is happening on the car or your battery is the problem. Load testing a fully charged battery should tell you how good it is. I don't know if this is still the case, after the gateway module, the next favorite battery drain problem used to be the trunk light staying on. But you can check that through the ski hatch.
 

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Discussion Starter #5
Whilst the Canbus modules should all be put in standby/sleep, there are some active modules. These include the immobiliser and alarm and where most of my 50mA comes from, but I'm happy with that. Testing volts drop across fuses is a handy trick, but there are some car electrics and electronics which are not fused at all e.g the alternator diode stack and charge controller. Trying to convert the mV reading to Amps current is error prone because different value fuses and contact holders have different resistance. Testing that way is only any good to confirm current is being drawn, if you want the real figure you connect the ammeter in series with the fuse. But whenever you do that you have to turn off the ignition and back on.

The interior lights are electronically controlled by a dimmer/timer to turn them off. If you break any circuit to insert a MM in series, as long as you turn off the ignition first then turn it on and then off to watch the current drain, that should be O.K because all the modules should boot correctly then shut down (after 10 Min) when the key is off. If the MM circuit is broken after switching on the ignition, I think this creates an abnormal system condition?

The discharge current you measure in series with the battery tells the truth but I wouldn't agree that pulling a fuse is 'daming evidence' because modules on that circuit may be good but not getting or responding to the CAN shutdown message. Isolating modules with their fuses could interfere with the CAN shutdown process, because messages expected won't get back to confirm they have shut down and other dependent modules may stay alive.

If I put an ammeter in series with the battery leads it takes about 10 minutes for my CAN to go to sleep. From memory the current started at about 180mA then dropped to 50mA, but when I had a bad Chinese cloned Gateway module I got bad battery drain. If you or somebody has uprated the radio and replaced the Gateway module, check that isn't your problem. You will find a lot about the Gateway module causing battery drain problems, but I suspect these are the Chinese clones like the one I tried. Are you sure all the modules are genuine V.W and some haven't been replaced with Chinese clones? If any modules have been replaced as DIY repairs, even V.W genuine, there could be compatibility issues with older modules. If V.W do the work they fit a newer replacement part, check the version status of older modules and reflash or replace any that may be incompatible. Of course they can't do that with Chinese units.

I might use the mV readings across a fuse to confirm current was being drawn, but never to get an accurate measurement of current this small, because results will change with fuse value and contact resistance. The total current measured at the battery (I don't use a Hall D.C clamp for these low currents) should approximate to the sum of current drawn through each fuses plus a small extra for any unfused circuits.

Your alternator is charging because you measured 14V. The only thing that matters is the actual current draw measured in series with a battery lead and the condition of the battery if it is old and self discharging. As a rough guide, if you measured around 100mA self discharge and never used the car, you will get the approximate time to dead battery (well probably work to 30% for sufficient charge to start it). If your self discharge is much faster then either something intermittent is happening on the car or your battery is the problem. Load testing a fully charged battery should tell you how good it is. I don't know if this is still the case, after the gateway module, the next favorite battery drain problem used to be the trunk light staying on. But you can check that through the ski hatch.
To answer some of your included questions/scenarios;
  • I bought the car from the local dealer as a "demo" with 7,800 miles on it. That was high mileage for a demo IMO but I got a great discount and a cool-ass car.
    • I have no reason to suspect that it was other than the OEM radio or they would've tried to charge me for an upgrade.
    • I have done nothing to change the CANBus or any other relays as a DIY
    • I don't know of the dealer changing out the CANBus for anything but they had the car numerous times for the problems with that dang transmission that they swore didn't exist until VW came out with a recall for the exact problem I had been describing to them
  • The car has only 33k miles on it now and I have replaced...
    • Tires at ~12k miles
    • Brakes (ceramic) at ~18k miles (I think around then)
    • Batteries in March 2019 (red tops for yellow tops)
    • Batteries last week (red for red)
I'm not trained for this stuff. At. All.

Is there any relay somewhere that can be swapped to try to get lucky, based on my fairly confident point that the Steering Column fuse is drawing up to 100mA while asleep?

And thanks for your thoughtful responses!
 

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Discussion Starter #6
Redo of alternator test:
Lunchtime, prior to starting, at 12.61V
Immediately after starting, at 14.15V
After running idly 10 minutes, at 13.82V
After running idly 10 minutes, at 13.73V
After running idly 10 minutes, at 13.65V
Is this slow decrease normal, especially since it’s still above 13.6V?
 

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I don't know what you are trying to prove? When a lead acid battery isn't being charged or just after starting the car it's voltage should be about 12-13 volts and rises quickly to about 14.5 volts when the alternator is running. Once the alternator considers the battery fully charged its regulator backs off and the battery voltage reduces to around 13.5 Volts. The faster this happens is just an indication of how discharged the battery was and how much the alternator needs to put back. I tender MY07 24/7 which takes less than 5 minutes running for my battery voltage to drop back. This tells me my tender is doing a good job and the battery is fully charged. I also use my low tech. ears when cranking.

As for your other problems, you may be out of your depth suggesting relays when these cars run with interconnected computer type modules and diagnostics requires a completely different type of tool kit and approach. Start changing modules here and there and you may have to do coding and re-adaptation which you can't do without diagnostics and the correct compatible V.W modules which can be expensive to buy just on a whim.

IMHO I think you need to get a competent auto electrician with 'eyes on' looking at your car, even somebody other than V.W if you aren't happy with them? YouTube videos only work for exactly the same faults but many assume their fault is the same as the post from a YouTuber. Modern cars are electronically complex and unless your battery drain problem exactly fits the same fault when there are so many computer modules, you best bet is to have somebody experienced work on your car.

You haven't said if your car has been scanned? Battery drain faults are unlikely to show up, but something else might give a clue to an experienced technician looking at your problem, even if its a check with the mothership that all the installed modules have compatible firmware.

If you car has been serviced by a V.W Stealer, they can do module firmware 'upgrades' without telling you and we know what happens with MS Windows! If your drain problem started after a service visit, I would think about that possible connection? There are often reports of recall modifications being done on car brands and consequential faults being introduced requiring a further recall.
 

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Discussion Starter #8
lol. Not trying to prove anything other than to have someone agree that my alternator is doing its job I’m in an all out data acquisition mode to hopefully gather enough to gain confidence that the stuff in the middle of the curves is legit
The YouTube comment was more for a laugh. And yes, I’m in over my head but trying to learn as much as I can about the conditions and approaches so I’m less vulnerable to wasting a lot of cash when I end up taking the car to a tech who may not be the most adept or forthright.
And about the relays question... I only brought that up as a result of talking with a gearhead friend in the neighborhood who has owned and worked on his own numerous VWs for his whole adult life so your comment about this car being more advanced was absolutely spot-on. I just read the whole relays thing as a simple Nope as an answer to my question.
i was going to scan it but my ODBII scanner isn’t iOS compatible and I no longer have an Android device. I have a new Fixd scanner arriving this weekend (only $20 so worth a shot).
So far, this has all been about investigation and getting legitimate data. I’m still wondering if someone can tell me what the diagnosis or treatment is, once it’s determined that there’s something going on with fuse F16.
 

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Diagnosing complex faults with several outcomes relies on getting a lot of relevant information to start with and that's what a good trained technician with the right training and tools is good at. Don't expect diagnostics to tell you exactly what is wrong and you go and fix it. It's just a helpful tool in the right hands. The human brain, ears and eyes are still the best tools to collect information and process it until AI becomes more mature. But don't hold your breath on it coming soon for DIY, because manufacturers will only invest in it to make money for their own repair shops after making their vehicles even more complex than they already are.

The V.W service network has one big advantage over your DIY attempts. They can access their huge historical database of faults and repairs. Gathering data is one thing, but gathering the right relevant data and understanding what it means requires more than an internet search or YouTube. A technician skilled at fault finding will go down many paths doing tests, collecting data, symptoms, and analyzing results.

The tool most workshops don't have or the skills to use is a CANbus analyzer and proprietary V.W system design information to go with it.
 

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Discussion Starter #10
Well, with all my amateur diagnostic adventures, I blew fuse 15 (“Interior Lights”) and had not realized it.
Surprisingly, however, my parasitic drain seems to have totally been resolved.
Every time I go to open the car I’ll check the voltage & it’s at a steady 12.62V.
If going without interior lighting will solve this problem, I’m good with that. However, does anyone know of anything else that that fuse powers?
 

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A trunk light permanently on is a common source of battery drain problems. Look through the ski hatch when the lid is closed. Are you sure the interior light switches at the top were all off or in their 'auto' position ? It's easy to leave them in the always on position. It annoys me they didn't illuminate the buttons.
 

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Discussion Starter #12
Well, with all my amateur diagnostic adventures, I blew fuse 15 (“Interior Lights”) and had not realized it.
Surprisingly, however, my parasitic drain seems to have totally been resolved.
Every time I go to open the car I’ll check the voltage & it’s at a steady 12.62V.
If going without interior lighting will solve this problem, I’m good with that. However, does anyone know of anything else that that fuse powers?
 

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Discussion Starter #13
A trunk light permanently on is a common source of battery drain problems. Look through the ski hatch when the lid is closed. Are you sure the interior light switches at the top were all off or in their 'auto' position ? It's easy to leave them in the always on position. It annoys me they didn't illuminate the buttons.
Thanks, I'll give that a look but have to wait for some fuses to show up from Amazon.
My cabin lights were definitely off, but on the auto setting. The red LED is still working without that fuse.
Do you know whether the TrunkLight-Always-On issue is an easy one to fix?
 

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Very little is an easy fix. you have to confirm if you have this problem first.
The red LED is still working without that fuse.
If you mean the red led on the drivers door capping? That's the immobiliser & nothing to do with interior lights.
 
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