transmission coolant valve failure? and electrical failure galore light dance on cluster

[amowolves]

Hi All

Any body else had this issue?

I was driving my 2016 A7 3.0ltdi stronic all seemed normal and all of a sudden I got all kinds of electrical failures pop up on dash. at one point the whole cluster went off and then came back up. tcmps, brake, light, start stop failure etc etc. spolier pops up by itself, the mmi screen opens and closes like nothing i've seen before.

So I pull up on the roadside, do the usual google and find that app (according to a couple of forum threads and a video on youtube) that a faulty coolant valve leaks and can send fluid down the loom to a gearbox sensor (next sensor on the loom) and causes all kinds of electrical mayhem.

So I checked my coolant level and low and behold its practically empty. Cars gone into my local independant garage and im waiting for to hear back from them.

But app its a common fault and audi have a TSB for it. but have not issued a recall.

anybody else had this issue.? my cars a 2016 and done 60k. my mrs said that a coolant level error popped up a week ago but cleared itself.

 

[Bishop187]

It’s defo leaking onto a electrical plug or two, judging by all the lights coming on on ur dash.
But could be leaking from anywhere.
Another common issue is the oil cooler, which is located in the V of the engine. It’s hard to see but the coolant pools up there.
Good luck


Sent from my iPhone using Tapatalk

 

[amowolves]

ah man what a headache. Well they checked the suspect coolant valve and it was bone dry as was the mulit pin plug that goes to the gearbox. no signs of coolant leaking at all.

However, I have asked him to replace the solenoid anyway, so will see on sat if it fixes the issues.

From further online research I've done, it seems it could be a number of things:

* low voltage on battery,
* a n other faulty sensor....another usual culprit seems to be the abs sensor.
* or as you say another common fault is the thermostat by the oil cooler in the v of the engine....so that could also explain the coolant leak.

They have however done a pressure test on the coolant for over 2hrs and there were no signs of a leak.

either way I'm getting the car back on sat so will try and get the vcds on it and get a full diagnostic report.

 

[amowolves]

So I have had the usual suspect coolant valve/solenoid replaced (in position N509) and it didn't seem to be the issue unfortunantly. It still could be one of the other two valves but since there didn't seem to be any coolant in the connectors, wiring loom or gearbox multiplug and as the existing valves are already the upgraded parts revision D, its not likely. They did a pressure test on the coolant for 2 hrs and no issues were found so maybe it being low was just a coincidence, as i've never topped it up in my ownership unless Audi did it during servicing.

I was able to get a new bosch battery and test if this was an issue, but after clearing the errors and driving around for a bit the issues simply came back. so its not the battery either.

after more research I am now thinking it could be the wheel speed sensor or the abs bearing in the hub? app it brings up the errors that i am getting and is a common issue. so i have ordered 4 new wheel sensors and having them replaced aswell as an inspection of the wiring/connectors in case there is any damage/corrosion. I did have the discs and pads changed by my local garage a couple of months ago so they could have broken/damaged something.

fingers crossed.

 

[amowolves]

Well I replaced all four wheel sensors....and....no good. Still get all the malfunction errors.

So that's coolant valve, battery, wheel sensors all replaced and no joy.

The errors don't pop up if I'm idling only once I start driving. So I supose the issue could be in the hub or other abs components.

Have ordered a new vcds cable so hoping to get more conclusive error report in the latest version of vcds maybe.

 

[amowolves]

Does this look like a healthy battery? This is with the engine idling. I did try a new bosch agm battery temporarily and it didn't seem to clear my issues so I put the old battery back in. But now I'm wondering if it could still be the original varta agm battery thats faulty. On start voltage does dip down to 12.1v.

 

[amowolves]

So I just been out in car again. Drove about 2 miles. Thought I'd check battery again after a drive and it showed the below on idle. And then upto 14v this time when idling. However I did notice the voltage drop to 10.8v when starting engine. I'm sure I read it shouldn't drop below 12v when starting? Thoughts...I'd it worth me trying a new battery again and coding.

 

[amowolves]

Hi All,

Just thought I'd update this thread as I think I may have found the issue! Its been a very stressful couple of weeks and after spending nearly £400 changing perfectly good parts it looks like that's it is the central gateway that is faulty or a short in the wiring loom that leads up to the unit under the rear seat bench.

I literally spent the day yesterday going back over the car from front to back, checking the ecu, fuses, relays, battery etc and I noticed it started glitching whilst I was parked with the engine running. It has never done this up until now, only when driving. So this got me thinking is it the vibration of the car that causes it (i.e a loose connection).

Anyway after banging away at the dash (around where the bcm1 module and relays are) I suddenly managed to replicate some of the glitches, particularly as I moved toward the rear of the car.

Then I remembered that in all my research over the last couple of weeks, amongst all the other issues that could have caused similar symptoms (battery, coolant valve, speed sensors, abs bearings, faulty relays etc.), I did come across one chap who had exactly the same errors but in an Audi A6 C7. He did say that he was able to replicate the issues when his kid moved across the back seat. so that got me thinking I may have a similar issue here.

When I started pressing around the rear seat, in the area of where the central gateway is, the mmi started going crazy and the instrument panel lit up like a xmas tree.

So I removed the rear seat bench and pulled the unit up, gave it a couple of firm taps, checked the connections and wiring loom. I started putting hand pressure on the unit and the wiring loom and it was no longer pinging errors at me.

So I reset the errors via vcds and took it for a long drive! hey presto! No errors! I was finally enjoying my car again, so I put it into sport mode and went for a good 20 mile blast up and down various different roads and highways.

Today I have put the rear seats back this morning and asked my kids not to sit in the middle. Did the school run and drove to work. So far so good!

So if this happens to you, and you get various errors - tpms, brake, stop start, abs, park brake and/or your mmi and instrument cluster randomly reboot or you loose your indicator, wiper controls and speedo. check the central gateway! Other symptoms i had was that I occasionally could not start the ignition and the dash would not power up, when this happened I also could not lock, unlock the car. VCDS basically showed malfunctions in virtually every module but nothing conclusive. Just lots of intermittent- no communication or missing messages errors. So i'm guessing either the faulty module or a short is flooding the can bus communication system causing all the other modules to go crazy.

Anyway, glad I now sort of know where the fault is.

 

[amowolves]

Ok thought i'd update with latest findings. So initially as above I thought it was the central gateway or a short around the module. But the errors re-appeared when i took the car to my local car wash and asked them to clean the inside. anyway long story short, the errors re-appeared and I tried to replicate what i did the last time to fix the issue but this time I could not get the car to stop pinging errors at me.

However, what I realised was that i could get the errors to ping more often if i pushed against the centre console. so here's me thinking it might be a loose connection in the rear of the centre console i.e the ac controls. but before I started striping that out i realised what i had inadvertently been doing all this time was actually moving my body weight around the drivers seat and every time I applied force to the centre console or rear seat, what I was also doing was applying the opposite force to my drivers seat since I was sat in it! so i started moving around in my seat and i could make the errors ping more regularly.

so I got under the drivers seat and checked that all the connections were firmly connected. booom all errors suddenly stopped pinging. been driving the car for a bout 3 weeks now and touchwood no issues re-appeared yet. This makes more sense now as I was also getting the air bag warning light coming on and of course there are airbags in the seats and what must have caused the errors to re-apprear was the car wash guys moving the seat back and forth to hoover the carpet!

what a ball ache!