OEM MK4 management wiring => Mk1/2/3 harness install FAQ (Now with added dieselness!)

ah you're doing a mk5 type r32 swap then? this guide isnt so much use to you then as the later looms are pretty different layout. the mk5 r32 ecu is very similar pinout wise mind, and soem of the tricks here do still apply to the later looms. I have diagrams in my signature for both mk4 and mk5 types so you can use those to help you out a bit.

heres a copy n paste of a mk5 t14a plug I have to hand, can see right away its quite different!
T14a - R32
1 - blk - oil pressure switch
2 - yel/red - crankcase breather heater (ignition live)
3 - pur/red - carbon canister
5 - red/grn - coilpack power (ecu relay live)
6 - blu/red - N205/308/156/80 valve (ecu relay power)
8 - red/blk - fuel injector power (ignition live)
9 - brn - coilpack earth
10 - red/grn - coilpack power (ecu relay live)
11 - pur/red - aux. coolant pump

the other thing is there are no plugs joining the big ecu plug half to the interior loom, its all hard spliced. so its a case of strip the loom, follow all the wires from the mk5 ecu to the inside and pull/cut them out where required. the upside is all the wires are mega long so you wont have to extend as many of them at least

 

Oh and I recently foudn this link, heres how you can get a VSS input to the ecu and enable cruise control even:
https://www.fastforward.ca/signalprocessors/

 

whats the engine code just to double check? but if I mentioned can-bus adaptor before we probably decided it was a MK5 type, so yeah basically near as damnit a MK5 BUB wiring wise

 

alrighty so then you need can-bus modules for tacho out and vss in, the link i mention has both separate its a shame they didnt just build it all into one unit for easy swaps but hey ho.

from memory the MK5 r32 coolant flange has a spare sensor hole in it, or at least has an extra sensor you dont need so you can put a mk2 2 pin black one in there leaving the mk5 ecu 2 pin sensor alone. its possible the mk5 ecu sensor is the same rating as the mk2/3/4 ecu sensors, but I haven't checked this. if it was then you could go for the 4 pin mk3 8v sensor trick, but tbh if theres a spare hole i would just bung a mk2 dash sensor in there for an easy life.

with both diagrams and my guide you should be able to get thru it easy enough, but if you have any questions feel free to ask

 

The BUB engine code is MK5 era, so its very different to the MK4 and so this guide isnt a great deal of use on the wiring side but a few bits n pieces will help you in my notes section.

rev counter and vss are both can-bus on these, so to get the signals in and out you need something like this:
http://www.co-star.co.uk/prod/4106/can-bus-rpm-interface.html

or these:
https://www.fastforward.ca/signalprocessors/

ecu pinout on the BUB engien is very similar to the earlier MK4 R32 though, so that may help you when figuring out the wiring side. I've both MK4 and MK5 r32 diagrams in my signature. Main issue with MK5 is the main ECU section is completly integrated into the main car wiring, so you have a lot of unpicking to do. but its also a good thing becasue it means you'll have lots of length to work with, unlike mk4 looms which need extending to suit mk3 engien bay routing. swings and roundabouts as they say

 

its a case of start with the ecu plug and chase all the wires back to source, pulling the plugs out on the other end without cutting where possible i.e. throttle, clutch and brake pedal and snipping wires off with as much length as possible for the other feeds such as power and earth etc.

what I mean is the pins on the ecu plug itself are mostly the same as found on the mk4, so if unsure of what function a wire is on the mk5 diagram you can try looking it up on the mk4 diagram, then compare to my list to try and work it out that way if that makes sense?

a few pins arent there at all on the mk5 side, main ones you care about are rev counter and vss input which as I say are done via can-bus so no wires for them in the loom. also no functionality in the ecu either for these pins if you try to be crafty and add the wires in on the off chance like I did on the first MK5 R32 loom I converted

 

hopefully someone will step in and start making units which take vss in and tacho out for a decent price now MK5+ engien swaps are starting to get more common.

I've seen people experimenting with arduino units, theres a guy who is using one to interface later polo can-bus cluster with driving games so it cant be hard to reconfigure the unit to pull a rev counter signal out of an ecu rather than inject it, and his code already injects the vss signal to can-bus so I assuem the BUB ecu would be happy with it too...
https://hackaday.io/project/6288-volkswagen-can-bus-gaming

also
https://forum.arduino.cc/index.php?topic=59378.0

 

depends what you like really, late mk2 and early mk3 use scapa rayon fabricy tape, then later mk3 switched to normal insulation tape, try 3m, scapa make for this. mk4 era have a mix of insulation tape and more fluffy type tape, on ebay its either no-name brand or coroplast make

personally I like the scapa rayon tape but thats just my preferance

 

Hello David, If you get a MK4 based n/a 20v such as the AGN, then the wiring should be the same as described in this thread

I do make wiring looms still but my list is long and my free time is short, but I can try to help you through it

Try to get the ECU and wiring loom to go with the engine, but it probably wont be hard to adapt a 20vt loom to suit your engine so long as you get right type to match the ecu you plan to run, DBW have completely different plugs on than DBC for starters. If you go ahead with it first confirm the ECU code/part number then we can work from there