sullyj

I experienced an issue about a week ago where I started the car without incident, drove about 20 yards and the gear cluster/dashboard warning lights all lit up and the car loss power. I waited a couple of seconds and restarted the car without incident. I drove the car for about 5-6 days flawlessly (about 300 miles in total) and when I was starting car again the same issue occurred. After two attempts the car started up and I drove it directly to my Audi indy shop (all their techs are ex-Audi dealership techs). They did a diagnostic and several codes appeared (I did not see them so I don't have the codes) a few which the tech says he's never seen before and they puzzled him. Interestingly, once he finished the diagnostic test the engine light now came on and has been on since. Additionally, where the starting issue was sporadic, it is now evident just about every time I attempt to start the car. In each occasion the car will eventually start after a couple of attempts, but I'm not comfortable driving it under the current circumstances. Last time car was in the shop (about two months ago for rotor/pad replacements) the tech noticed the battery wasn't at full power and suggested I replace it before winter hit hard. Is there a chance the issue may be battery related? Please note this is a replacement motor which was installed around Jan'18 (long story) with about 55,000 miles on it. During motor replacement we changed/replaced all items which could be reasonably replaced O rings, clamps, hoses/belts, and any items on my old motor that had been recently installed ( ignition coils, fuel pressure units etc..). Any suggestions here? Obviously with the gear cluster issue one thinks tranny, but it shifts flawlessly and I don't see many issues with the D3 transmissions ( as compared to the D2's). Does the D3 have a neutral switch?

MP4.2+6.0

Be more specific on what lit up in the inst. panel. Especially, did the gear shift display reverse its normal appearance? See the picture of the display in the original post (#1) to this thread as an example. https://www.audiworld.com/forums/a8-...oblem-2909311/ Did it look more or less like that?

sullyj

I'm tempted to say yes that the display lit up as you noted in the photo (gear shift display reversed normal appearance) but I'm at work now and the car is at home and I'd want to check to be sure.

sullyj

Good morning. Found out the issue was a weak battery. Battery was replaced with am OEM unit and it seems one of the rear headliner located vanity mirrors was the culprit. The light would come on occasionally and it was draining the battery. Unfortunately my indy shop can't program the MMI so it's now non-functional so it's off to the "stealer" next Tuesday to be programmed. This is the only car of dozens I've owned that needs programming after a battery replacement.

Jack88

Most of the time, the car will learn in time after a battery replacement, but programming fixes it rate away. It's just a matter of changing a digit in the battery's recorded serial number, it takes a couple minutes to do if you know how. But you need a tool for a computer to talk to the car, like the HEXCAN from Rosstech. If they charge you an hour's labor, you might as well just buy a cable so you can do this and other things yourself in the future. Or just resell the cable when you are done.

sullyj

Thanks Jack88. Good advice.

MP4.2+6.0

Again, need more specificity of the issue here.

Described literally, whether MMI is working or not really has little/nothing to do with a battery replacement. As Jack mentioned, the only thing you" program" is to tell the car it has a new battery for purposes of the load management calcs. If things like your remote to unlock and lock the doors is working, it should have enough juice for other optional things that the load management system controls. If lots of the "extra"things (not core to car running like ignition and headlights and such) are not working, suspect continuing battery issues. If other auxiliaries do work but not MMI, suspect fuses or other issues. Overlapping Jack's point, the VCDS (VAG-COM) cable again pays for itself--where first you program in a new battery, and then scan for issues with MMI as examples.

sullyj

MP4.2+6.0,

Thanks for the feedback. Well, best I can share is the MMI screen is completely black but all other functions in the car seem to be working fine (except bot the front seat warmers went out at the same time). The tech at the indy shop is a former Audi tech at a dealership and given I don't have his level of Audi expertise I guess I have to deal with the "stealer". Given the lack of seat warmers I definitely felt there was a fuse issue involved but I guess I'll find out Tuesday when the dealership gives me their diagnosis. As far as a battery drain, the passenger rear vanity mirror light would sporadically come on and go off and I noticed over the last few weeks or so that when I started my daily commute the light would be on because the connection to cut it off has become worn. I'd wedge it with a small cardboard shim to do a temporary fix that really wasn't working well. Car now has a new battery and I have my fingers that the fix won't be too major.

MP4.2+6.0

If MMI screen is completely blank, a WAG might be a heavy fusible link back in the same area as battery. Look at the fuses there, particularly at the bare metal ones shaped like long dumbbells held by metal nuts. See if one is burned through. I had that once on my D3 A8 when local body shop did some work to other areas but presumably disconnected battery. Turned out to be one of those fuses IIRC. Obviously if you change one yourself be careful with tools there--disconnect battery again and/or carefully use a nut driver.

sullyj

MP4.2+6.0,

Well the fun continues my friend. After installing the new battery, other than the MMI issue, the car was driving flawlessly until I took it to a hand car wash center. Immediately after driving from the car wash the gear cluster lit up and the engine light came on. I had to nurse the car home (no limp mode...just restarting the car when it would cut off which happened three times). The car will start up and idle fine now, but the engine light is on. I have to believe water has gotten onto some sort of electrical connection which is causing the current issue. I had the sunroof channels cleaned abut two months ago because this is my second A8 and I've been down that road a few times. Any idea what item could be exposed to water getting to it to cause this problem?