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ECM Swapping

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ecm swapping
8K views 16 replies 5 participants last post by  keithwbloom 
#1 ·
Hey Guys,

I have a 2001.5 (NEW) Passat 1.8L T with an ECM issue, according to the mechanic and I need to replace the ECU.

I have an old ECU from an identical vehicle which I need to program into my car.

I tried programming it into the new car with the following instructions but had no luck.
I got to the PIN stage and had to stop because I didn't have the pin.

Immobilizer IV ECU Swapping - Ross-Tech Wiki


Is it possible to obtain the PIN number from the original ECM in the car using VCDS?, then applying it to the replacement ECM so it pairs with the car?
 
#2 ·
Not sure in Canada IMMO, but in USA the VIN is stored in the ECM and it will not allow you to program the IMMO info if the cluster and ECM don't have the same VIN. The easiest way for you would be to get the cluster and key from the donor car, and swap the key blade from your car. You will have a car with a different VIN than what the modules are saying (so a potential problem when you do emission inspection) and wrong miles (the miles are easy to change).
 
#3 ·
As far as I know, no - not even the VW dealer can extract the PIN; they do re-programming while connected to the dealer network, which uses it but does not display it. I believe their are some aftermarket software programs than can do this, however.

Edit: I don't think the miles are that easy to change; certainly you can't do it with VAG.COM except on new clusters. There are good reasons for this to be difficult.
 
#5 ·
Is this a software that will extract the pin I require, as per ROSS TECH instructions.
I don't want to spend the money and find out it doesn't work.

As far as I understand, once I get this new pin, swapping and programming the ECU shouldn't be a problem. Am I missing something?

Also, IMMO = immobilizer....... correct?
 
#8 ·
OK. As I understand it, VAG Tacho is a piece of software with doubtful provenance; I see it offered various places at various prices. (I've seen $50 to $950!) The closest I could find to an official site was HERE. Most likely, most of the copies offered are illegal; I have some doubts as to the legitimacy of the publisher itself. I would recommend attempting to contact the company that "makes" it to find out the exact capabilities; or perhaps just buy the cheapest copy offered and try it.

Everything I've read indicates it will extract the PIN code. As far as allowing the immobilizer to be programmed - dunno. And yes, IMMO = immobilizer.
 
#7 ·
Yes, that tacho unit should allow you to read the PIN.

But like I said before, I don't think you can swap the ECU because you will have a different VIN on the ECU and cluster.

On one occasion when I messed with this issue (it was a bad cluster actually) I replaced both the ECU and cluster from the donor car, and left the VIN alone. If you come to TX, I know someone here that can program the correct VIN.
 
#13 ·
The reason IMMO was invented: only a dealer (which is a trustworthy shop) can program various functions. If anybody can do it, it kind of defies the purpose. Tacho is probably a semi hack/semi illegal hardware and software, just for that reason. I didn't research the origin but I bought one cable a long time a go and used it a few times with success.
I would buy the cheapest one, and install/run it on a cheap computer that you don't want hacked :)
 
#14 ·
I forgot: when you install the new ECU in your car, it does not get your VIN. The VIN is already programmed into the ECM and you can't change it (AFAIK) with tacho. The IMMO starter disable is stored into the cluster, but the cluster will have your car's VIN and if this VIN does not match the ECM's VIN, it will not start the car.
 
#15 ·
Okay, okay, okay, okay.

First things first. No, you cannot modify ECU VIN and IMMO encoding with Tacho. But you can with Galletto and other ECU programmers. I am not going to go into the details here, but I will go you a trove of information to review if you want to attempt an ECU swap with a used part. I have done it several times, all related to stockpiling and swapping tunes in my 2004 GLX with two ECUs until I learned there was a third cable I need to rewrite the ECU safely in the car. Up until then I was doing ECU swaps using encoders and EEPROM utilities on a bench harness.

Read up. It is not light reading. But the ending is happy.

And your technical questions would best be answered by the the gurus of cluster coding and ECU tuning, polo-mk3 and k0mpresd, respectively.

Start here (though you can read back in the thread for background if you have an hour to kill).

Somewhere in that thread I found a command line utility that can rewrite the 98040 chip in the ECU where the IMMO and PIN data are stored. But you have to use a hex editor and a clean accurate copy of your old ECU dump and a clean read from the new/replacement 98040 chip as the base before you edit. You can read the PIN info from the EEPROM dump from the cluster. When you have the PIN and IMMO from the cluster (using tacho to dump hex code and then IMMO and PI are stored as specific addresses depending on cluster year and chassis type) you can graft it in and make the needed checksum edits in the ECU 98040 EEPROM with the command line tool.

Your IMMOs will then match, and your replacement ECU should fire right up with your existing key and cluster.

But all of this intervention requires some pretty technical harness fabrication and a bucket of brass balls because futching it up will brick your cluster and/or ECU. I know this from personal experience. Fortunately, all the goodies you make and/or acquire for recoding clusters and ECUs are about 90% of what you need to fix a truly bricked ECU or cluster motherboard.

Have patience. Else find someone that has it. It is not an easy task to undertake, but when you are done, it make a lot of sense in retrospect the things you had to do. I found it immensely rewarding to turn the key every time I recoded my ECU and cluster and I must have done the ECU a dozen times in as many days when tweaking maps, and the cluster at least half that many times again as I was swapping in and out my original cluster with a pair of platooning W8 clusters while I was repairing their FIS displays.

:lightsaber:
 
#16 ·
Well, the rest of us are offering bits and pieces, whereas keith knows - as usual. Correct me if I'm wrong, but it would seem as though amassing the necessary software tools and expertise to do this is in the purview of the really dedicated hobbyist, rather than someone who simply doesn't want to buy a new ECU. Yes?
 
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