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

Discussion in 'Engines' started by rubjonny, Nov 8, 2013.

  1. rubjonny

    rubjonny Administrator Staff Member Admin

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    You can wire is to 428 or whatever relay really powers ecu and all coils via 1 fuse, the rest its up to you. the mk4 golf has it all fed from the fuel relay split across several fuses, the mk5 has some stuff powered from the ecu relay and some by engine electrics relay

    as you're going separate fusebox you're free to choose whatever works best for you :)
     
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  2. Nari_vw New Member

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    And buddy what you think about use auxiliar water pump on swaps??
     
  3. DamienC New Member

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    Cheers John. When u say start with ECU relay or power to it do mean use a multimeter to check I've got a consistent 12v at the ECU?
     
  4. DamienC New Member

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    Cheers John. When u say start with ECU relay or power to it do mean use a multimeter to check I've got a consistent 12v at the ECU?
     
  5. rubjonny

    rubjonny Administrator Staff Member Admin

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    I would if it had one originally, the audi a3 just uses a simple timer relay similar to any aftermarket item you can grab from ebay so its not hard to sort out


    first check for good permanent live feed at the relay ignition off, on and cranking, check the output side is only live ignition on and cranking. the relay should click and then this powers ecu and coils
     
  6. Sniki New Member

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    Hi @rubjonny , i am the guy doing the 24v R28 VR6 swap into a 1994 mk3 gti pulled from a VW Sharan, it's been a while since i left the project aside due to time limitation and work / first time father etc.
    Today i finally removed the front again and removed the two sensors on the coolant flange/Thermostat housing and wrote down the part numbers, we were having trouble to know what each sensor does and why are there two of them so we can replace it with the MK3 sensor so we get temperature reporting on the cluster.
    The sensors are:
    1. Gray color: 06A 919 501A, W2k5 , EH2 140* max, 30-10
    2. Brown Color: 7M3 919 369, ELTH , 42-00

    I also remove the rubber cover from the connectors of each sensor to see wire colors:
    1. Gray Connector wires: Blue and Brown
    2. Brown Connector wires: Brown/Blue and brown/white

    Here are also two pictures of each of them, the brown one is flat inside, the gray has some sort of a tip.
    brown-connector.jpg brown-shape.jpg gray-connector.jpg gray-shape.jpg
     
  7. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    1. Gray color: 06A 919 501A, W2k5 , EH2 140* max, 30-10 This is the coolant temperature sensor for the AYL engine the range is -40 to 140 deg C
    2. Brown Color: 7M3 919 369, ELTH , 42-00 This is the switch for the additional coolant pump.
     
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  8. Sniki New Member

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    Thanks so as per post #1 i should remove the gray sensor and fit the MK3 sensor and modify it's connector so i can have both the cluster to report correct temperature into it's gauge and also have the ECU happy with it as @rubjonny suggests on post #1 into coolant section as Mk3 sensor works fine with the mk4 ecu.
    Although i don't have the additional coolant pump (not sure i will need it or not), i see a lot of people getting rid of it however i may leave it's sensor there as i think it works also as the after run thermal switch. am i correct ?
     
  9. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    I own cars with these engines and conversions. So speak from my own experience.
    For a MK3 Cluster, you would use the 4 pin square sensor with G62 and G2 combined. These have NTC curves that are expected back at your ME7.1.1 ECU, as well as the profile required in the MK3 VDO or Motometer cluster for engine temp.
    I run a BDE engine in my MK2 Golf, which runs the G62/G2 sensor I described, as well as a MK3 VR6 cluster.
     
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  10. Sniki New Member

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    Im not quite sure which sensor are you refering as G62/G2 ?
     
  11. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    [​IMG]

    [​IMG]

    G62/G2 are two sensors in one.
    It was replaced in later PQ34 vehicles (8L S3, 1J V6 4Motion, V5 20v etc) with a D shaped black and then green sensor.

    G62 matches the requirments for a ME7.1.X ECU, however in the square sensor, G2 matches the engine temperature requirements of a MK3 cluster.
     
  12. Sniki New Member

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    Thanks, however it’s a me7.1 not 7.1.1 if that makes any difference.
    And are 357919501A or 6U0919501B supposed to be G62 sensors or they are different ?
     
  13. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    The AYLs use a slightly different ME7.X ECU than the 022906032BG ECUs in BDEs. I have a few of them here.
    But it makes no difference to the engine or performance, for Sharans or Ford Galaxys.
     
  14. Sniki New Member

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    I wanted to ask on how should i route the Big ECU connector wiring harness on a MK3 GTI (the one that contains the o2 sensors, Carbon Canister, SAI, the MK4 Relay Box, etc).
    I did strip down all the MK3 harness from fusebox and removed all the unnecessary wires from it, however i don't know how should i properly route the Big ECU connector harness to fit and reach properly.
    The Engine harness from a VW Sharan AYL cable reached the hole in the middle of the engine bay and reaches the scuttle fine and plugs into the ecu (where the previous one - MK3 used to be), however im not sure how to route the other part of the wiring to fit well on the scuttle/bay.

    Any suggestions ?
     
  15. rubjonny

    rubjonny Administrator Staff Member Admin

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    On RHD wiring looms the way I do it is have the new ECU in the same place as the old one. Route the loom so the big ecu plug half comes in through the right hand scuttle hole along with the wiper motor wiring, plus I also drag the left repeater wiring back through the right hand hole as well. This will then leave the left hole where the old ecu loom used to come through completely free for the small ecu plug half to use.

    as you have a LHD car this may not work as well for you, so YMMV. at the end of the day as long as it works and doesn't cause you too much extra hassle do whatever you like
     
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  16. Sniki New Member

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    Since the engine was taken from a VW Sharan, the engine loom is a bit shorter than a MK4 but it reaches enough through the middle hole of the scuttle area and reaches perfectly fine the ecu where the old ecu used to be mounted/placed.
    As for the second part of the loom, i may have to cut/open up that middle hole of the scuttle area all the way up and get part of the cable with the relay 100 relaybox/MAF cable and the wires that go to the battery/starter, the right side goes out fine for carbon canister and lambdas wire and the mk3 wires go in through there just fine till next to the ecu where i will solder them with the brown/white/black/orange connectors then plug them in together.

    One question though, since i do have the relay box, on the big ecu plug loom, there is a thick red positive cable that goes to the battery, on post #1 do you refer that that cable powers the ecu relay and can be use for the permanent ecu live feed + coilpack so its 2 birds with one stone situation ?

    Also old MK3 loom had an earth for coilpack thick brown brown/white cable (not sure which one was but it's written on the cable sticker that i left note of) which was use for the 2.0L 8V engine earth for the coilpack, should that one be fine for the coilpack earth on the new engine, i believe it goes under the battery tray anyway ?.

    And last the MK3 immobilizer, in order to remove it, what should i do with the wiring, is there any wire that needs to be kept and wired somewhere ?.
    I remember it was causing me problems on first/cold startups where i would've cranked infinitely and engine won't fire but the second i turn the key back and crank one more time, the engine would start instantly.
     
  17. rubjonny

    rubjonny Administrator Staff Member Admin

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    That large live wire sounds like the power for the SAI relay, if you're getting rid of that you can re-purpose it to use for your ecu relay instead which means you dont have to pull any power from the main fusebox inside the car. if its similar to mk4 you'll have several spare fuse holders in your relay box as well which I make use of for my looms

    the mk3 coil earth is a little thinner than the original, personally I run a new thick earth for the ecu and also the coilpacks straight to the battery or earth stud under it when I make my looms up just to be sure

    for the immobiliser you can just leave it all in there and ignore it, or drag it out if you prefer. the wiring for it is all separate from the main loom so can be taken out without disturbing anything else, its just a bit of a pain to do thanks to the mk3 kneebar making everything much harder than it would be if you had a MK2 :lol:
     
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  18. Sniki New Member

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    @rubjonny I am a bit confused, i kept all the OEM setup including the SAI pump which i placed it where the Air Filter housing/box used to be on the 2.0L 8V engine.
    Only Immobilizer is what i removed myself with CH341 Flash Programmer +SOIC8 Test clip.

    On the Big ECU Plug loom, i do only have the Relay 100 on that small black fuse/relay box which as you described i assume is the SAI relay.
    However regarding the ECU relay, this is where i am confused, where is the ECU relay, is it possible i don't have it or using the one from MK3 ?, confused there.
    I would like a description on what to do with my current setup, where to place it, where to take/pull wires from and where to run them, etc.

    T6 Brown connector:
    Pin 1 ---> G2/4 Since it's fused right ?
    Pin 2 ---> G1/3 (G1/3 that's fine, done that)
    Pin 3 ---> N/A
    Pin 4 ---> Permanent live to ECU, so as i understood i should run a decent feed wire straight from battery, am i correct, is it needed to be fused, if yes what how many amps should the fuse be ?
    Pin 5 ---> Where would you prefer to wire this Blue/Yellow cable to, since i have both lambdas, Carbon Canister, and SAI valve
    Pin 6 ---> N/A

    2nd confusion place:
    T14a/7 Sensors Power ----> where would i preferably wire this to ?
    T14a/8 Injector Power -----> same as above, prefered wiring spot and if fuse is prefered how many amps
    T14a/9 Coilpack Power ---> where would i wire this one as well, you mentioned 20a on post #722.

    I think i am fine with the other parts and managed to fire engine and have no error codes on engine side however the way i fired is T6b/1 - G2/4
    T6/4&5 - a straight wire from battery.
    T14a/7&8&9 - straight to battery.
    But now that i am wiring it and soldering it the right way, that's why i am asking the above so i can do it the right & recommended way.

    Thanks.
     
  19. rubjonny

    rubjonny Administrator Staff Member Admin

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    ok your donor harness didnt have an ecu relay, depending on age/engine/car they sometimes wont.

    G2/4 isnt fused, but on your loom its only going to be the ignition switched power for the ECU so its no big deal. non of the mk1/2/3 ecu feeds are fused, but feel free to add one in if you like

    permanent live feed to ecu again isnt fused on mk3 golf so thats up to you. if the big ecu loom had an ecu relay on it though T6/4 would also be the main live input for the ECU/coil power relay which is why I mention to fuse it in the first post as you definitely want a fuse on your coilpack power feed. doing it here will also fuse your main ecu live so its 2 birds with one stone

    T6/5 if it was just 2 lambda heaters I would run it to G1/8, as the US spec VR6 has 2 lambdas on this pin. Any more than that I would run a fused feeds from Z/1, the relay box in the engien bay has 3 or 5 spare slots I make use of those. On heavy looms with lots of accessory feeds and/or cars with the older ceramic fusebox in the past after deleting the SAI system I have re-wired the SAI relay to function as an aux power relay. it already has a fuel relay power feed on the trigger side so you just earth the ecu pin and run the output to a selection of fuses. The later VR6 has all the engine electrics except lambdas running direct from G2/8 and Z/1 with no fuses, so again up to you on that one

    t14a/7 you can run this to a switched or fuel relay power whichever is convenient. G2/4 is fused by a 10a fuse already and would be handy if not already in use
    t14a/8 fuel injector power, ignition or fuel relay live. on late VR6 its powered direct from Z/1 with no fuse. If you want to add one, 10a or 15a same as MK4 v6 engines. 10a on early ones, on 24v models the injectors share a 15a fuse with the ecu ignition feed on T6/1 so you could poiwer ecu and injectors from G1/4 with a 15a fuse for example to replicate that. on the sharan the injectors are fed straight from the fuel relay along with the fuel pump and both are fused from a 30a feed.

    t14a/9 I would wire this to an ignition switched relay
     
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  20. Sniki New Member

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    Ok so conclusion to this:
    T6/1 & T14a/8 - Wire these with G1/4 since it's free and add a 15a fuse.
    T6/3 - Since my harness doesn't have an ECU relay then i should wire that straight to battery if i understood correctly.
    T6/5 - While Sharan does have only two lambdas, i do have the Carbon Canister, SAI valve and that would take more load so at this point would G2/8 be able to handle the load or i should use the Z1 instead. Both options are available so i can pick whatever you recommend.
    T14a/7 - will use G2/4 then since it's free and gets powered same way with ignition as G1/4 does.
    T14a/9 - Which relay should i use in this case and what would be your recommendation on this one specifically.
    T6/3 and T14a/9 are being the biggest headache due to the lack of the ECU Relay as that would've been a lot easier if my loom had one.

    Thanks again !.
     

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