dzcad90, I got about halfway through installing an MFA in an A3 Jetta before I sold the car. But I got far enough with it to know that it is basically the same process as with the B4 with a couple of exceptions: some of the MFA wiring is missing from the 28-pin cluster harness and there are some differences in internal MIL circuitry between early and late A3 GLX clusters (you should use the later style). And Christi is right, a UK cluster is not an option for a US A3/B4.
Jonathan, I'm sorry to say that I'm only part way through a complete revision of the conversion article. Among other things, it includes an alternate (more elegant but more costly) method of dealing with the tach.
It sounds like you're interested in getting the MFA operational now and worrying about the tach later, so, assuming that's the case, I can supplement the article with updates pertinent to that goal.
1) If you aren't able to find a used wiring harness for the stalk controller, p/ns for the 2 connectors used to make your own harness are:
357-907-968
1HO-953-635
These come w/o pins (I don't have the pin p/n, sorry).
2) If you simply install the unmodified GLX cluster and controller on a plug-and-play basis, you'll have all MFA functions except oil and air temp. Note, though, that you won't have a functioning MIL (nor, of course, an accurate tach). The GLX's MIL will actually be functioning as the glow plug warning light.
3) I do recommend a rebuilt cluster from the dealer vs. a used one from a wrecking yard for a couple of reasons: It may actually be cheaper, when you figure in the additional cost of reprogramming odometer mileage for the used cluster. And you eliminate the risk of winding up with a cluster thats been previously weakened or damaged by low voltage. If you go with a rebuilt unit, you may have a struggle getting it ordered with your current odometer mileage pre-programmed, as dealer parts departments are generally not aware that this is available, but it is (and at no additional cost).
4) Odometer (and MFA distance) accuracy should be fairly close to what it was with your original cluster, but I would check it. GLX overall gearing is a little shorter, but tire OD is a little larger, so it seems to be a wash. If the inaccuracy is excessive, there is a solution, but there is some cost involved ($80). Speedometer accuracy is actually a separate issue and can be corrected at a later date (at no cost) when you break open the cluster to deal with the MIL.
5) I assume that MPG reading accuracy will be important for you now, and, unfortunately, it will probably not be very accurate as installed and will be somewhat time consumming to correct. Its not difficult but involves changing the pump's Injection Quantity value, then waiting till the next fillup to gauge the results and repeating this process several times. I can give you the value that worked for me, but it may not translate to your particular pump/ECM/MFA combination.
Well, this should get you started. Let me know if I can be of help.
