Audi TT dash swap, EEPROM

**rosak** · 17th July, 2017, 10:29 AM

Hello and welcome everybody.
I recently started playing with VAG instrument cluster and I got to the point where I need your help.
I have customer with his dash having an intermittent fault. It's Jaeger dash 8N2920980A. During driving, the temp/fuel gauges suddenly return to 0 and the LCD resets.
I replaced all pointer motors to brand new ones but that didn't help. It happens also on my desk, when I twist the whole board- that tells me there is some dry solder joint somewhere but I couldn't find it.
I resoldered everything around LM2902D op-amp and A82C250 CAN controller as that's where I thought the fault is but it didn't help.
Now I don't have these dash with me, customer will be back tomorrow.
I'm going to look further into the board but if I don't find it, I will try to swap it to another instrument cluster with the same numbers 8N2920980A. I read that with Audi it's not that straightforward. I was going to desolder EEPROM chip from customers dash and solder it into the other dash. I think it should work with no issues, but what do you guys think?
Only thing I am afraid of is to make the customer's car not starting again and I don't have these expensive interfaces to get into ECU etc.

I know I may be asking for too much help and I don't have reputation on forum yet, but I am going to be active here and try to help others as well.

Thanks for any help.

**immokill** · 17th July, 2017, 12:00 PM

Ok that dash is known problem. dont desolder eeprom read old pin and new dash pin and you will adapt it to car using vc ds.

**rosak** · 17th July, 2017, 12:17 PM

Thank you very much for your response immokill.
Could you please guide me a bit in reading pin's and adapting it to the car? All I have for now is an old VAG-KKL cable and old VAG-COM software, will it be enough to do that?
I'm going to order some more recent interface and software from Ross-Tech but customer is going away in a few days so it won't arrive till then.
Also, why do you think swapping EEPROM chip is not a good idea?
Before doing anything above I will be trying to find and fix the original fault anyway, especially if you say it's a common fault, that could help other people on forum too.
I know I'm asking for much, but I don't have time to do own research with this particular customer.

Thanks a lot

**exe123** · 17th July, 2017, 12:21 PM

You cannot swap any eeprom as these magneti marelli dashs have none. All integrated into the MCU (Freescale 68HC912)

**rosak** · 17th July, 2017, 12:59 PM

Thank you exe123.
This is not Magneti Marelli, it's Jaeger one.
And to be honest, I don't know now if it does have EEPROM anyway. I didn't take a picture of the whole back of the board and I will have it back tomorrow.
There is a big SOIC20 chip which I cannot find a datasheet for but it has "0511MBU MEGAMOS RES" markings. A quick google search suggests that it may have something to do with immobiliser data.
Even if there is an MCU with integrated ROM instead of separate chip, there is also not a problem for me to swap it, unless this is the chip which is responsible for original fault.
If I gain enough information from you guys, I may buy the newest VCDS software if that's the only way to swap these instrument cluster. I rather invest than keep the customer here for hours.

**lbnsky** · 17th July, 2017, 05:48 PM

Yes it is jaeger is made by magneti marelli. You have to find the biggest chip on board it's moto hc912 and there are few points close to that hc912 solder 4 wires vcc, vss, bkgd, rst and read it with programmer (upa, orange5 etc). You can find any info on dk. When I swaped the dash in a3 or tt, I copied eeprom area from old one do new one in most cases it work.

**rosak** · 17th July, 2017, 06:34 PM

Thank you lbnsky. I already figured out that MM & Jaeger means the same. Unfortunately the only programmer I have laying around is EZP2010, it only programs 24, 25 & 93 chips.
So I will either figure out how to make my own programmer using some ATmega or STM32 or how to reprogram and adapt the second instrument cluster using VAG-COM 409.
All I know for now is that my VAG-KKL cable supports K-line only and not CAN but it reads this dash data so I believe it should do the job. I'm just not sure whether the "soft code" is the PIN which you're talking about and if the "Adapt" button will let me do everything I need. I'm a bit concerned about IMMO data.
Like I said, I might be able to fugure everything out myself but I don't have the device. Customers coming tomorrow evening and I'm trying to gather as much information as possible to not keep him waiting for too long.
Another option is still the first one I was asking about, take the whole HC12 from faulty cluster and solder it into the other one. But I'm still not sure what about IMMO data.

PS I just figured out how to thank you guys for help

**rosak** · 18th July, 2017, 08:21 PM

So I ended up desoldering both HC08 and HC12 and putting them to the other dash. The only difference between these 2 clusters were that one was M73 D05 and the other one M73 D09. No idea what that means, anyway, the car engine started up as normal, but the immo yellow checklight keeps flashing. Customer just rang me to say that after about half an hour driving dash started to beep constantly.
Any ideas?