tadc-- The new clusters use the Immobilizer III system, which is new as of '02 models. You will notice that SVTWEB has a '02 TDI. From what I can tell, this third generation system is much more adaptable than the second generation system we have ('99.5-'01), as evidenced by the drastically fewer number of available clusters; whereas the old system appeared to be more hard-coded to each vehicle--each cluster had to be custom ordered for a specific vehicle from the plant--the new one can be programmed for most anything. Now, I cannot tell you for certain that an Immobilizer II cluster cannot be transplanted, as I have not tried it; but when I was dead set on having a MFA in my car, this was the problem.
My hope is that the essential function of the immobilizer is to facilitate communication between the ECU and the cluster, and that all that is required for this to happen is (a) for the ECU and cluster to recognize each other as the expected hardware and (b) for the ECU to recognize the key as the appropriate key. Then, if one can tell the ECU to expect a different cluster, regardless of what sort of cluster it is, swapping clusters won't be a big deal. Perhaps VW will only produce clusters for specific vehicles so that they can keep track of clusters, not because the hardware requires it.
On the other hand, the cluster itself could play a crucial role in recognizing the key or authorizing the ECU. If this is the case, and the cluster is from a different vehicle--not only a different key, but also a completely different ECU type if from a GLX--would not be happy in its new environment, and wouldn't allow the car to run. Then, if the cluster itself cannot be reprogrammed, nothing works except for perhaps a few seconds at a time.
One hint that the Immobilizer III cluster can be reprogrammed whereas the second generation cannot be is on
APR's website; it mentions that the ECU can be adapted to the cluster for a second generation system without requiring any cluster-specific work, whereas the newer system requires "cluster ID numbers," implying to me that the cluster is flexible. Another is the question, what if I could just swap one cluster for another?--then, I could take a high mile car, swap in a low mile cluster from a scrapped car, and sell it like a low mile car; I don't see VW allowing that, but this could just mean that the cluster's odometer value cannot be changed over the swap (which is true, but is there more to it?).
My guess is that older clusters, with the Immobilizer II system, can only be programmed once and before any usage, and only for two things: mileage, and key. The Immobilizer III system perhaps can also be adapted for each ECU, although I suspect this too can only happen once.
More questions than answers, I fear, but I hope this helps.
