| When doing a TT conversion, the TT fuel pump is mandatory while the TT Fuel Pump Controller is arguably "optional". Some have had reported good luck using the NA controller with the TT pump and others have reported excessive fuel pump noise. The NA fuel pump controller (FPC) runs the pump on "high" speed at all times. The TT fuel pump controller utilizes a second "low" speed for low-load conditions in an effort to reduce noise and extend the life of the fuel pump. The following writeup illustrates the differences between the NA and TT wiring harnesses which must be addressed when swapping a TT FPC into an NA. This writeup does NOT cover swapping the actual FPC or fuel pump, only the wiring differences. An Error in the FSM
According to the FSM, there are NO wiring differences between the NA and TT with regard to the FPC. In the snapshot below you'll notice the (TC) or "turbo only" designator is not present next to the purple wire on Pin #35. This purple wire connects the ECU to the FPC via three harnesses and some of the NA harnesses do NOT have it. 
Schematic
Here is a crude schematic to help clarify the pictures in the sections below:
 In the sections below I'll work backwards from the FPC to the ECU illustrating the differences between my 1990 NA 2+0 and my donor 91 TT 2+0. Body Harness
Starting at the white connector for the fuel pump controller (located behind the driver's seat), you can see the purple wire in the Body Harness which continues to a blue connector located under the fuse block (by the driver's feet). This is the purple wire I mentioned above which eventually connects to Pin #35 on the ECU. The blue connector connects to a female blue connector on the Fuse Block Harness which, in turn, connects to the EFI harness. My 90 NA actually had this section of purple wire in the Body Harness, so at least some NA's (all?) have this portion of the overall circuit. Don't assume this to be the case though, verify the presence of the purple wire when you install the FPC. 
Fuse Block Harness
This is where the differences start to appear. Looking at the mating blue connector, the pin for the purple wire is missing on the NA Fuse Block Harness:
Here's another view from the rear of the NA connector: 
The TT Fuse Block Harness has the purple wire, so it needs to be transplanted (or substituted) to the NA Fuse Block Harness. In my case I was able to de-pin the TT harness and swap the wire right into the NA harness/connectors. Here's a picture of the brown connector at the other end of the TT Fuse Block Harness (connects to the EFI harness) and you can see where I've de-pinned / removed the purple wire: 
EFI Harness
These pictures show the EFI Harness connectors which connect to the Fuse Block Harness under the hood (next to the relay box). This is probably the clearest illustration of the difference. You can see the factory plugs in the NA connectors where the TT connectors have wires (one for the 2-spd A/C fan and one for the 2-spd fuel pump): 
I purchased a 95 TT EFI Harness for my swap which obviously came with the necessary wires (fan and fuel pump) shown above. If you're using an NA EFI Harness for your swap you'll need to replace the missing wire(s) on your harness. In my case I needed only to connect this purple wire in the TT EFI harness to the existing purple wire on the NA Body Harness by transplanting the "missing link" in the Fuse Block harness. I'll cover the second missing wire in a separate writeup for swapping the 2-speed fan (also considered "optional"). Again the pics are from a 1990 NA 2+0 and a 1991 TT 2+0. I have not inspected a 2+2 or various years, so there may be differences throughout the years and models. Nevertheless, when swapping in a 2-speed FPC you need to verify that the associated wiring goes all the way back to the ECU.
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NA to TT, starting from the ground up... Proper check valve inspection per the FSM...
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2-speed fuel pump controller wiring (for TT conversions) - 
