Reference pictures for standard harness cores
MK4 1.8t & VR6 & TDI
Notice ecu has two plugs. The smaller plug off ecu is all of engine harness. The larger plug (referred to as body harness) contains the 02 sensor leads, a small e-box located near brake booster, maf plug and will terminate under the wiper motor in cowl area. There is a small plastic black cover with two 10mm nuts holding the “cover” to the body. Remove this cover and simply unplug the harness from the interior wiring via the 4/5 colored plugs. For TDI motors some harnesses will have a separate glow plug relay and socket and some will have a glow plug relay located in a small fuse panel under the dash above clutch pedal area. the socket and relay or at minimal the glow plug relay itself will be needed for the harness.
MK3 ABA, VR6, TDI
Starting with ecu follow the harness to engine twist lock. ABA and VR6 motors you may leave the small harness on your motor unless it looks to be needing repair. TDI engine (1z & AHU) please include the harness off engine. The main body of harness will enter into the cabin of car in driver corner under coolant bottle. Feed the harness through the grommet hole. A friend is very helpful for this process. The harness will fully unplug from fuse box and all components under dash. For TDI motors be sure to include the large #180 relay mounted to top edge of fuse box (this is the glow plug relay and required for harness build and testing).
3.6 BLV & 2.0T & 07K
Notice ecu has two plugs. Smaller ecu plug off engine is all of engine harness. The larger plug (referred to as the body harness) contains the o2 sensors, plugs into the fuse box in the engine bay, maf , and various components in the bay. This harness needs not be cut in the engine bay- it unplugs from all its components. Locate where the harness passes through the firewall into the interior of the car. This grommet is an irregular shape and may be ripped or cut. Pull the harness away from firewall and cut the harness on interior side of grommet, this will net a usable body harness for building. The only items you will need from the interior are the throttle pedal plug (you need keep pedal with you) and the fuel pump module with plug from body that lives over fuel pump, under back seat. The fuel pump module is not applicable for 07K harness cores.
Fuse Panel Identification and Plug and play Requirements
Late West Fuse Panel Harness
Located behind the fuse panel you will find a black 10 pin plug. this plug will detach and will need to be in its entirety be removed from the mk1 engine bay (may contain one or two relays attached to fuse block as well that can be detached from the fuse panel). Incude this harness if you are requesting a plug and play option for this fuse block type.
CE1 required harness
The harness pictured above must be removed from the donor car- uncut- for a CE1 plug and play option to be completed. This harness will contain the wiper motor harness and various oem chassis engine wiring.
CE2 required plugs
While not absolutely required but always appreciated the two plugs pictured (G1 &G2) will comprise the plug and play portion for a CE2 compatible swap. The remaining plugs concern the oem chassis wiring and will retain. If you are doing a MK3 swap it may be advantageous to contact TDC Shop and discuss the services of removing the engine portion of the wiring from the current engine bay harness.