Another basic ecu question

[DG2004]

I’m sure this has been answered before on here I just can’t seem to find it. I have a 2004 a4 1.8 6 speed. The ecu died. If I swap out the ecu with one from the exact same year/model car is the immobilizer still a problem? Is it better to just buy a plug and play? Thanks.

[rollerton]

I’m sure this has been answered before on here I just can’t seem to find it. I have a 2004 a4 1.8 6 speed. The ecu died. If I swap out the ecu with one from the exact same year/model car is the immobilizer still a problem? Is it better to just buy a plug and play? Thanks.

There's no such thing as 'plug 'n' play. How do you know ECU died? No CEL when key is turned on? Can't connect via OBD?

There's almost no way to adapt a different ECU to your car without addressing the Immobilizer. You could get an ECU w/ Immo off and it should run- but you'll have errors in the cluster and warning beep and other hassles.
It's fairly easy to deal with the Immo these days though. Many people can adapt the ECU pretty easily with VCDS and a program to get the SKC...

[grayjay]

Immobilizer SKC is individually set between the ECU and instrument cluster, a replacement ECU (even from same model year) will have a different SKC and will not let the engine run if the SKC does not match. ECU has two different data storage location, the EEPROM chip is sort of like the BIOS for the ECU and holds data specific to the car such as the SKC, softcoding, immobilizer and VIN number. An alternative to VCDS re-adaptation route for the SKC, you can use a bench harness, open the ECU to activate boot mode use nefmoto tools to either edit the new ECU security code to match your old ECU & Cluster SKC to keep the immobilizer working, or you can turn off the immobilizer function on the ECU entirely. If you do the later, just be aware that you will not be able to program new keys to the car, the immobilizer must be active for new key programming to work.

[DG2004]

Do the pre tuned ones with immo off that you can buy like the ones from boost dynamics make the car have all weird errors and hassles to deal with? That’s what I meant by plug and play.

The car still has cel OBDII working, but does the crank no start and randomly starts sometimes. . Then has the ecu code. The code goes away when it does start, and I did notice the temp guage will randomly max out and stay. I put a different temp sensor in and unplugged everything and it worked for an about five minutes. Already did the usual relay, fuse, ground checks. Any thoughts?

[DG2004]

Is it possible to just swap the eeprom chip without destroying it?

[Cybersombosis]

It’s relatively easy to adapt a new ECU to the car. Just get one from the same year and trans to make it easier. You will need a cheap blue VCDS eBay cable and either a licence for that cable or a genuine VCDS cable. Follow the directions on the below link to get the SKC and then follow the procedure from Ross Tech to adapt the ECU to the car.

Retrieval of SKC from old and new ECU.
https://sites.google.com/site/imnuts/home

Adapting Immo to the new ECU
https://m.youtube.com/watch?v=J5_51qeEyec

[rollerton]

It’s relatively easy to adapt a new ECU to the car. Just get one from the same year and trans to make it easier. You will need a cheap blue VCDS eBay cable and either a licence for that cable or a genuine VCDS cable. Follow the directions on the below link to get the SKC and then follow the procedure from Ross Tech to adapt the ECU to the car.

Retrieval of SKC from old and new ECU.
https://sites.google.com/site/imnuts/home

Adapting Immo to the new ECU
https://m.youtube.com/watch?v=J5_51qeEyec

I don't think VAG K+CAN Commander will pull SKC from B6 ECU.

You'd need different software to get SKC, and be very careful you can wreck the cluster with one wrong click.

[Cybersombosis]

I’ve pulled many an SKC with Vag K Commander as per the Imnuts instructions from ECU’s. The OP will need to do that as he will need the SKC from the donor ECU in order to adapt it. I’ve done it a bunch of times as I’ve swapped in ECU’s from various B6’s we’ve had come through the shop. The key secret to farting around with retrieving the SKC and adapting immo is that you never ever write to an ECU or cluster with these programs. That is where you can screw something up.

If all he needed was the original SKC, I would have told him to use Vag EEPROM Programmer to get it from the cluster but since he needs the SKC from the donor ECU, that program won’t work.

[DG2004]

Thanks for the help guys. Why am I not just putting the skc from the old ecu (its not totally dead) in the putting it new one if it’s the same model/option car? Shouldn’t everything work at that point I feel like I’m missing something.

[Cybersombosis]

Thanks for the help guys. Why am I not just putting the skc from the old ecu (its not totally dead) in the putting it new one if it’s the same model/option car? Shouldn’t everything work at that point I feel like I’m missing something.

Exactly. This is what I’m telling you to do but in order to do that, you need the SKC from the donor and old ecu which Vag K Commander can retrieve. The hardest part about this whole thing is getting the cheap eBay cable drivers to work properly. The rest is pretty straight forward and paint by numbers.

[rollerton]

I’ve pulled many an SKC with Vag K Commander as per the Imnuts instructions from ECU’s. The OP will need to do that as he will need the SKC from the donor ECU in order to adapt it.

Interesting- I've had a couple versions of Vag K+ Can for 20 years, I have never once had it work on a B6 ECU. It's like Vagtacho, it just doesn't interface with any of the 4 cables I have.

It would be nice occasionally if I could make it work.

[DG2004]

Exactly. This is what I’m telling you to do but in order to do that, you need the SKC from the donor and old ecu which Vag K Commander can retrieve. The hardest part about this whole thing is getting the cheap eBay cable drivers to work properly. The rest is pretty straight forward and paint by numbers.

Awesome! Got it. I don’t mind spending the money on not eBay stuff that is known to actually work. Recommended brands?
I do metalshaping/ restoration for a living and I’m just getting into newer ecu based stuff for fun and learn. This car is a hobby car. I figured Audi is a good place to start they aren’t crazy expensive and pretty sporty. So I don’t mind spending money on higher quality tools. I’m also a tool whore 😂 It may be a car guy thing.
Thank you guys I really appreciate the guidance.

[Cybersombosis]

The cheap cable needs to be FTDI or it won’t work. I’ve never used Temu but it’s cheap enough.

https://share.temu.com/vHLwlEXzwjA

[EuroxS4]

Why bother spending money on a ECM when you can diagnose the problem? When it cranks but doesnt start does the tach move? If no it needs a crank position sensor.

[Cybersombosis]

Do the pre tuned ones with immo off that you can buy like the ones from boost dynamics make the car have all weird errors and hassles to deal with? That’s what I meant by plug and play.

The car still has cel OBDII working, but does the crank no start and randomly starts sometimes. . Then has the ecu code. The code goes away when it does start, and I did notice the temp guage will randomly max out and stay. I put a different temp sensor in and unplugged everything and it worked for an about five minutes. Already did the usual relay, fuse, ground checks. Any thoughts?

What ECU code is it giving? That may help us help you diagnose like EuroxS4 said.

[DG2004]

It’s 0688 code. Intermittent starts code goes away let it sit for ten min. Won’t start code comes back. Fuel pump, crank sensor, relays. fuses are good to go.checked over wiring/ grounds found the typical toasty coil pack wires made sure they weren’t shorting and no misfire. Just got the car. Thermostat or water pump is bad would a shorted thermostat sensor do weird crap to it? Still not positive it’s not a short in wiring or in a sensor somewhere. Any search tips that are usually suspect on old b6 a4’s? That I haven’t listed?

[Cybersombosis]

Check to see if there is water in your ECU box. Then swap out the relay labeled 219 in the below picture and see if that helps.

IMG_2883.jpeg

[DG2004]

Check to see if there is water in your ECU box. Then swap out the relay labeled 219 in the below picture and see if that helps.

IMG_2883.jpeg

All ready swapped all the relays in the ecu box out with new and I also have another b6 runner to double check if parts are good. It’s strange that it will randomly start and run fine then it sits it sits for a bit and then it won’t fire off. This one is an interesting challenge. I’m sure it will be something stupid. At least it’s not a daily driver.

[grayjay]

Vag K Commander program has a button labeled KEY LEARNING. I don't have VCDS to do key adaptation and I was thinking it might be possible to use Vag K Commander instead. Here is what I found;
I got a spare key cut and a new virgin RFID chip, wanted to get it adapted to my immobilizer-on ECU. I connected Vag K Commander, read the ECU/Cluster SKC and then tried the programs KEY LEARNING feature. I first re-paired my original (working) key and then added the new key. It was successful with pairing the new virgin RFID chip to the ECU immobilizer, car would start and run with the new key which previously caused ECU immobilizer to shutoff engine after 2 sec of starting. The gotcha catch is that Vag K Commander does NOT also pair the new key to the clusters (separate) immobilizer! The car will run and drive with just the ECU immobilizer working, but the cluster immobilizer causes the hazard lights to flash and the climate control system to lockup in SAFE mode. Same thing happens if trying to to use the new unpaired key with the ECU immobilizer turned off, there does not seem to be any way I can find to turn the cluster immobilizer off. I suppose the new key is at least still useful as an emergency lost key backup to be able to drive the car if the primary key is ever lost or broken.

Anyone else ever had success with any other non-VCDS alternatives for pairing a key to the immobilizer AND the cluster in an B6?

Most promising option I want to try next is a free command line program called kw1281test. More on this program at;

https://github.com/gmenounos/kw1281test/wiki
https://fiddly.net/mk4/mk4-vw-key-coding.html
https://forums.tdiclub.com/index.php...native.509151/

[willemml]

I wound up finding an unlocked copy of a recent version of VCDS Lite on one of the Russian forums. I need to find a place to get keys cut before I can actually do it though.

[grayjay]

I wound up finding an unlocked copy of a recent version of VCDS Lite on one of the Russian forums. I need to find a place to get keys cut before I can actually do it though.

The github program KW1281test worked for the new key adaptation;
https://www.audizine.com/forum/showt...1#post15163251