Since I just finished up on my install I thought I'd share it with the forum.
My A2 Jetta cluster started falling apart so it was time to put another cluster in. I got lucky and traded a GTI back seat for a very clean A2 Jetta GLi cluster WITH the MFA option! So I immediately decided to activate the features of the MFA cluster when I installed it.
First thing was the splicing of the cluster in to my current wiring harness. I had already spliced in the two plugs used by the previous cluster which was a CE1 unit. This new one however was a CE2 unit which uses one 28 pin plug instead of two 14 pin plugs.
I knew George had put up a wiring diagram with the correct pinouts so I immediately looked it up. That's when I discovered that my wiring was slightly different. Not sure why but it was easy enough to work with. The "new" wiring diagram is included later in this post.
I had already beaten the right steering column support down to clear the plug so I didn't need to do that this time. But it IS often necessary for a good fit. None of the screw holes in the cluster mounts line up but don't worry about them. The cluster will still brace up against the mounts and stay in place.
Biggest issue for me is always the lighting for the cluster. It's a big white plastic dome on top of the cluster and in my dash there isn't enough room for it. So I remove it and replace it with another source of light. You can get creative and use what you like but I use a 6" Cold cathode tube (like neon) for my lighting. It simply lays in the groove that exists BUT you need to removed the middle piece of plastic that keeps it from laying flat. Grab it with a pair of needle nose pliers and break it out. I used silicone seal to mount the tube. After you're done cover the entire lighting slot with tape or else crap will fall in to your cluster and not look nice.
You might want to note the small back part on the back of the cluster. That's the hookup for the vacuum hose which will allow you to monitor gas mileage. You'll need to snake a hose thru the firewall somewhere to hook this up.
There are several wires from the cluster that WON'T correspond to anything you have in your harness. That's because these are used exclusively to run the MFA display.
Pins 4, 5, 6 and 15 are used to switch and/or reset the MFA readout. These usually connect to a 4 wire plug that comes from the turnsignal stalk of MFA equipped cars. If you didn't get the signal stalk then you can still wire up your own switches as I did.
Pin 19 (outside temp) will require the outside temp sensor. It's still available from VW if you didn't get that when you pulled the cluster. Normally it's located in the left fender well behind the bumper. I'm planning to engineer my own sensor to monitor intake temps.
Pin 7 is for the "speed sensor" I assume this is a cruise control thing since I don't have one.
Pin 17 is for the oil temp. If you have a cabby you already have a guage for this. You can hook up this wire to the same sensor BUT it will read low about 40 degrees or so. The oil temp sensor the cluster expects is a higher temp unit evidently. You could retrofit the Jetta GLi oil temp sending unit but then your console guage would be wrong. Your choice of how to deal with it.
Pin on Single 28 pin Plug / Color on Big Plugmy color /Description / Color on MK2 CE1 Harness
Note the presence of several wires with the same color. Do not confuse them when splicing!
1 Green ?
2 Red/White Coolant Low Level Sensor (Directly on the low coolant switch)
3 Brown Ground
4 Grey MFA RESET
5 Brown/White MFA GROUND (Brown)
6 Green/White MFA MEMORY (Grey/Yellow)
7 Black/White Violet Speed Sensor (Blue/White)
8 Yellow Oil Pressure Control Unit 1.8 Bar (Gray/White)
9 Red/White Oil Pressure Control Unit 0.3 Bar (Blue/Black)
10 Green Tachometer (Red/Black)
11 Red Digital Clock (Red/White)
12 GreyInstrument Panel Lighting (Gray/Blue)
13 Black ignition switch (Yellow/Red)
15 Black MFA MODE SWITCH (Green/Black)
16 Blue Alternator Warning Light (Blue)
17 Black/White Engine Oil Temp (Green/Black) MFA
18 Yellow Seat Belt Indicator
19 Black/White Violet Outside Temp Sensor (Black) MFA
21 Blue Fuel Gauge (Violet/Black)
23 Yellow/Red Coolant Temp Gauge (Blue/Yellow)
24+22 Green+Brown/White Turn Signal Light (Green/Black) Join them together There is NO brown/white wire on my plug
25 Green White High Beam Indicator light (Black/White)
Now, If you have a dual plug cluster things are much easier with the wiring. Only difference is the oil pressure switches which you need to reverse. Yellow to blue/black and blue/black to yellow.
Here's how I made my onw MFA switches. The left switch switches between MFA mode I and II. One is the "this trip" readings and the other is "all the trips averaged together" readings. Resetting either is accomplished by using the right switch for about 2 seconds.
The big read button is for switching the readouts on the MFA.
The readouts are Elapsed time (since ignition was turned on) , miles driven , Averaged MPH, Averaged gas mileage, oil temp F, outside temp F. The MFA has a nice feature that doesn't reset the "this trip" mode everytime you start your car but waits about an hour between startings. That way gas and food stops won't interupt your readings.
Those living in Arizona should take note that the outside temp only goes up to 122 degrees
All the MFA readout swithes ground out to perform their function. Here's a simple wiring diagram.
There are several funky diagnostic modes that you can trick the MFA to read. Do a archive search in the A2 forum for MFA to find more info.