Hi all, I've got a 2015 Q7 TDI which recently went so dead that it was reading 5V and I had a few dash lights on, but the car was otherwise completely unresponsive. Could not get any buttons to do anything at all until I hooked it up to a decently powerful charger.

I did some reading around on here, and found all of the similar threads. So nice to have all of this information! I figured the issue was probably the door touch sensors, since none of them worked to unlock the car, and only one works to lock. Went ahead and clipped the number 15 wire in all four door harnesses, replaced the battery, and recoded it (although had to use a different code because even though it's a Varta and has BEM codes, VCDS wouldn't save the code). Then cleared most of the codes since there were a ton due to low voltage, cycled the ignition, and scanned again. I got three codes for Door Handle Touch Sensor Open Circuit, but curiously my left rear door is not reporting that code despite wire 15 being clipped. I am also getting a Central Locking Button Exterior Door Handle Implausible Signal on all four doors (guessing these are also expected after the clip) as well as Door Warning Light / Entry Light Electrical Fault In Circuit code on the right rear door. Haven't really explored that last one yet. Anyone know specifically which light it's talking about?

Fast forward a couple days, the car has been driven a couple times. I checked the battery voltage before bed last night and it was reading 12.40V. I thought that sounded a little low for a brand new battery, but since you have to unlock the car and "wake it up" to really be able to check easily, I thought maybe it was just dropping due to load from lights and such. Checked again in the morning and it showed 12.35V. I guess that's not bad for an overnight drain. Still, the battery was fully charged when installed two days prior and the car was driven a couple times for at least 15 minutes at a time. Am I crazy to expect the voltage to be higher?

I then started looking into this forum post and found a bunch of the CAN groups you can check in VCDS for battery and charging stats. Just went out and fired up the car (which was again at about 12.4V even after just being driven for an hour straight or more just 3-4 hours prior), updated VCDS because I saw there was an update available, tried to code my battery again, still didn't let me, and then ended up recoding it anyway for good measure. Not sure if it's a mistake to do this when the battery isn't fully charged, but anyway. I'll attach a couple pictures of what I was seeing. Basically, while the car was running, the Generator Voltage was reporting 13.5V, which again seems maybe a little lower than I'd expect. Battery Voltage reported was 13.2V and current around 3A. As much as 5A if I rev'd a bit. State Of Charge is reporting 100%, perhaps since I just recoded it.

After shutting off the engine and opening the driver's door, but keeping VCDS going, I saw that the Terminal 30 Voltage now shows 12.4V, Battery Voltage shows 12.6V, and Battery Current shows -6.1A (and was more like -15-20A when I first shut off the engine before some of the lights and whatnot shut off).

Does all of this sound normal? Just trying to figure out if I've still got a drain, or if I should just expect the battery to never really read higher than 12.4V? Also, still weird to me that I'm not getting a code for open circuit on one of the door sensors even with the wire clipped.


While running.

Engine off, driver's door open, a minute or two after shut off.

 

Are you using the adaptation path in VCDS to reset the BEM code, or going directly through the long-code programming and trying to manually change/store values? Odd that you'd be having that much trouble unless the manufacturer code is getting entered incorrectly. The VARTA battery code can be entered two ways, for example: VAO (the expected way, using all letters) or VA0 (which is VA+ #0, etc.), which is a quirk of the BEM system, so try them both.

If you replace the battery it is important to use the part # for the type of battery you bought...so AGM versus the Flooded battery are different part #s, but just the last few letters, etc., which tells the computer what it needs to know about the battery type/ Amp hours capacity, etc.

As you'll find out, you may have snipped wrong wire on that left, rear handle, thus the error codes mismatch, and also that the door handles exterior lock buttons also fail, which requires unplugging the wiring pigtail to the door handle inside the door panel to eliminate the drain. If those locking buttons don't work/ are frozen, then it is grounded and causing a constant parasitic drain. The wire snip/depin method only defeats the proximity sensor circuit in the handle as a simple, quick work-around, which leave the external lock buttons active still.

You may have other electrical drains on the car from other sensors and/or failed ground strap(s) in engine bay having corrosion inside them/developing high resistance. If you have access to to a FLIR camera or similar heat sensing device, these are easy to locate as they create a heat signature. Otherwise you gotta do the research on this topic, which has dedicated threads.

 

I was using long code programming to manually enter a new battery string, and I could test it but it would not let me save. I think it could be one of two things. Either it is unhappy that Varta's vendor code has changed (my battery says Varta and has the viewing window, etc, but the vendor code is CCL which is not listed in VCDS) or that the part number is 10 digits instead of 11. I had read that if you have a 10 digit part number, you just add an extra space before the vendor code, but for one reason or other, it wouldn't take it. Anyway, I just looked up the VCDS help page for battery programming and used one of the part numbers they had listed there that matched the battery specs.

Good to know about the battery type listings, I figured that was part of it but wasn't sure which part referenced that. My battery's part number from the BEM sticker is 000915089K but the one I used from VCDS is 000915105DL. Do you know if they denote different battery types?

I will definitely check those lock buttons. Hadn't thought of that. I am 100% sure that I snipped wire 15 on that door. I did pull the connector back out to check. Could it be that on that door, it's a different pin? Didn't sound like that from anything I read, but my logs seem to say otherwise. I guess I could always solder it and just disconnect that one at the handle instead. I also didn't know that the lock button can fail separately from the touch sensor, so I guess I am tearing into the doors now. From the sound of the posts I read, snipping pin 15 solved both issues.

Unfortunately I do not have access to a FLIR camera (though that would be awesome), so I guess I'll have to disconnect each handle and see what happens.

Someone also mentioned that it could be possible that leaving the dome light switch in the Auto position could cause drain, and that switching it to Off should fix it. Have you heard of that? It's certainly a little bothersome to keep it off since you get no lights when you get in at night.

 

Next time just run the adaptation to change the battery/reset the BEM system. The end result is same though. The battery part# you gave is listed as a VW T-Reg battery part#...it is equivalent to the Audi part # you actually ended up using for the flooded battery. Not hard to see why that was a problem for you...hopefully. Same part, but different part #...VW and Audi use diff part #s on everything they share....so Audi can charge more for them that have their logo stamped on it. Your Audi BEM system requires the Audi part#, etc.

The FLIR camera isn't for the door handles; it's for easily scanning over everywhere else on this car to detect any other drain source, lol. The door handles are a given they will fail. One thing about the wire snipping that can throw you off is all the wire at each door will be a different color/diff markings on them, even though share same location, so gotta focus solely on the correct pin location, not the wire color/markings.

 

Woops, I have actually been using the adaptation. I think because you said long coding, my brain related that to long adaptation in VCDS. Anyway, that's what I'm doing.

Interesting the VW has their own vendor code for Varta. Sounds about right. Anyway, sounds like it doesn't matter either way so long as the part number reflects the proper capacity, etc.

I wasn't saying to use the FLIR on the door handles. Wouldn't expect that to be helpful since the wiring is so insulated behind things.

I did read before snipping that the wires can be different colors. Interestingly, all of mine were the same color, except in the door that isn't reporting the open circuit. There is a wire of the same color on that door, but it wasn't going to pin 15 (again, I am 100% sure I snipping the right pin, it said 15 above it, and I counted back from 20 at the end to make sure) so I thought that was interesting that three of the four doors used that same wire and one used a different one for than pin, and coincidentally that's the problematic one.

Anyway, I'll be checking out the door buttons today to make sure everything works, and maybe tearing into them to unplug the handles,

 

Okay, more odd behavior. I noticed that despite not having the Open Circuit code on that rear left door, all buttons and functionality aside from the handle button work fine. However, on the rear right door, the lock button does not work. All other doors can lock the car, but not that one. I wonder if that's related to the Door Warning Light / Entry Light Electrical Fault code.

 

If you talking about the exterior button on the door handle not working to lock the car, then that indicates that button is grounded/frozen in place...it's dead. All of the exterior handle locking buttons will get that way eventually.

If you talking about the interior door button, then that would be linked to your actions and very likely what you actually snipped on the other door. It is really, really easy to make an error when using the wire snip method, especially if you think all the wires are same color/marking, as they are not.

 

It's the interior button not working on this door. I don't know what to tell you here. I guarantee you the correct wires were snipping on all four doors. I triple checked them all before snipping. It really is not hard to both look at the marking on the plug to verify that it's 15, and also count back from 20 on the last pin. Why would I have a code for open circuit to the touch sensor on this door if I snipped the wrong wire? Also, if you want pictures, I'm happy to send them to show that three of my four pin 15 wires were the same color pattern.

Just to reiterate, I was referring to two different doors in that last post. Left Rear door does not have an open circuit code, but all of the buttons work fine inside. Right Rear does have an open circuit code, but the interior lock button does not work.

 

FWIW: You are missing the point here. If you snipped/de-pinned the correct wire on the left rear door's pillar connection, then you'd be getting an open circuit fault code immediately on that door too...just like on the other three doors, where you did 'snip' the correct wire, or that fault code would not be visible. This car is networked together, so a problem in one spot often shows up as a symptom in another location. Revisit your 'snip' work on the left rear door pillar.

Good luck to you

 

I definitely get the point here. What I'm saying is that it IS pin 15 I snipped on that door. I triple checked it when snipping. I checked it again after seeing the the codes were different. And I checked it one more time yesterday. I am running out of ways to express that it is definitely pin 15 that was snipping on all four doors. Would it be helpful to get you a picture so you can read the markings and count the pins yourself? I feel like I've said this a few times now and all I'm getting is "you must not have snipping pin 15".

Let's just assume that I am correct and it was pin 15 that was snipped. How would that fit into the symptoms here?