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

Excellent John Thanks, really like that cig lighter idea. That's the one for me

 

Of course i thought of another related question...... Will these 3 wires (live, earth and k line) to the obd port be sufficient for remapping or do i need to connect the canbus wires too?

 

Thanks John, hard to fathom how an ecu can be reprogrammed on essentially one wire. All too much my little brain :-)

 

Hi guys, new to the forum here.
I did research for a long time and no one so far replied in any of the forums, hopefully someone can help there at clubgti.

Excellent thread @rubjonny as it made my life 1000 times easier doing my kind of more specific swap.
I have a VW Golf MK3 GTI, 1994, 2.0L 8V.
Due to the very limited amount of VR6 engines available in my country, the best i could find is a 2004 VW Sharan 2.8L 24V VR6 Engine with code (AYL).
Unfortunately the VW Sharan was already sold on half of it's parts...
So i took it and the parts that i currently have are:
- Complete AYL engine
- Engine Loom
- ECU
- Fuel Pump
- An O2A transmission
- ECU to Orange, Blue, White, Black, MAF, etc Loom (Second half of the loom was missing because someone needed it and he sold it to him/her. Got one from a Seat Toledo 2 VR5. with the relay box)

What i know that i am missing right now is:
- DBW Pedal
- Flywheel
- Starter
- VR6 Instrument Cluster/Clocks

I would appreciate if someone could tell me which DBW Pedal is going to be compatible (part number would help even more, will a DBW MK4 Golf 1.8T work ?), would like to know the same for the Starter and for flywheel.

Concerns/questions/doubts about the ECU:
In my country i barely managed to find someone who does defeat immobilizer, however im conerned about ABS, i would like to keep ABS if it is possible but i don't know if it will work plug and play, or if it is possible to code it into a MK4 ECU or will a MK4 ABS work or is the only option to do a ABS delete as well, as i heard that these engines may cause issues with rev hangs at specific RPMs without abs done properly or not deleted.

I do have Climatronic AC, are there extra steps beside those wires question marked for fan/climatronic being wired ?, what about Airbag as well.

Would like to get hints/tips for stuff that i miss that i haven't mentioned.

It's my first swap, i am a car mechanic but wiring/electrical stuff is something that i am kind of beginner, finding a mk3 vr6 donor car would've been so much easier but there weren't any on my country available till today, so i had to go the 24v route.
Budget was another factor too as i got this excellent condition ayl vr6 engine with only 120`000 km for just 350 Euros + 100 euros for the 02A, + 40 Euros for the 2nd half loom = 490 Euro total till this point.

Thanks in advance !

 

Thanks @rubjonny !

Thanks to that Seat Toledo II VR5, i took the Starter and the DBW Gas Pedal from it,
I visited a guy in a city not too far from me where he has a lot of used VR5/VR6/R32/R36/1.8T parts/engines/etc, he has a garage and does all the swaps besides the Wiring where he sends it to a guy/friend of him where he merges the wires of MK1/2/3 into MK4 Management.

He told me that my 2.0L 8V GTI front and back engine mount won't work as they are different, i grabbed the Flywheel, The Front Mount, The transmission Clutch cylinder (aluminium one), the pipe and the pedal clutch cylinder.

He couldn't find the rear mount as he had a lot of parts and it was dark already and his parts storage had terrible lightning.
He also said that the Radiator won't work as the hoses are on the passenger side instead of the driver side and due to climatronic hoses and small front clearance i would have trouble running coolant hoses through there.
He also said that the shifter box won't work, i have to use a TDI one or simply upgrade since you have to do it anyway and take it from a MK4.
I believe somewhere in forums I've seen people mentioning that the VW Polo Shifter Box will bolt right into the MK3 without a single mod, is that correct ?
As i know that the MK4 2 back screws of the shifter box will need some fab work to mount them.
He said he will find the rear mount and the Plastic of the Throttle Body from a MK4 as the one from the Sharan goes on top of the Intake Manifold and rotates to passenger side as that's where the air filter is located on VW Sharan and that will cause issues as the engine bay cap won't close as it will stay too high.

So questions in short:
1. Which Shifter Boxes are compatible/better/etc, i am a car mechanic and fabricating stuff won't be a problem for me but whenever i can use less work, that would be appreciated.
2. Brake Upgrades: my MK3 GTI 2.0L 8V golf does have 5 bolts and i believe 280mm discs if that's the standard of the 2.0L 8V GTI(s), which would be the best brake upgrades (from other cars), the rear ones are also disc brakes.
3. ABS: So as i understood, i will have to use a MK4 ABS instead the MK3 ABS Pump ?, and also is it possible as i believe my MK3 Golf does have abs only on front ?, i don't remember seeing any sensors on the back ?, Also aside from modifying the ABS Connector (if it is not the same plug as the MK3), is there any extra work needed for the ABS to work ?
4. Compatible Radiators or it only has to be a VR6 one ?.
5. Procedures on SAI delete, pros and cons, are they the same procedures or they differ 24v / 12v ?

 

Thanks @rubjonny
Right now i am cleaning parts like starter, aluminum clutch cylinder, etc into their aluminium and painting them. I did clean to pure aluminium and repainted my 02A transmission like brand new.
Doing the same with with the engine block, the head is aluminium already, so im just going to polish it, same for oil pan.
As for the intake manifold the Sharan does have it black, not aluminium color painted like the MK4(s).
Thinking that i may look better in aluminium color.

1. So for transmission you are saying that the MK4 is much better/smoother right ?, i have plenty of Polos and MK4 golf everywhere i look around, just VRs are very rare. So for shifter boxes i can get any of them for a joke like price. Max 30€.
Fabricating won’t be an issue and since those other parts are the main problem, I don’t think ill ever have the need to go back to it. I have another car.
And wether the engine fails or something, having to upgrade the engine won’t be a big problem anymore since i can only swap the engine and ecu and the tranny and other parts are going to be compatible (whether i decide to R32/R36 or something).

2. Will give it a try, with the 280mm as they are right now, if i see the need for upgrade and if those 312mm mk4 ones fit, that would be awesome as upgrading to those will be a piece of cake, thousands of MK4 golf(s) (90% of them tdi(s) ) in the scrapyards nearby.

3. Man you made my day, so the MK3 abs works natively/standalone without having anything to do with the ecu, that is awesome.
But does that mean that i have to do the ABS delete into the ECU or the MK4 ecu should recognize it ?.

4. I am just a bit worried whether people here can do SAI delete and such stuff, immobilizer Off that’s possible but not sure if they can do other stuff.
I should be able to keep the SAI if it actually has any single benefit by just placing it somewhere else, fab a mount and extend wires/hose.
Should research a bit more on who does those ecu services in my country.

Thanks for all the extended details, you really made my life easier with it.

I believe i am almost complete in terms of parts and knowledge on things that i have to do.

 

How can we mod ecu remotely, is there an easy way to dump the flash/file and send it for a modification?

 

Having an intermittent issue with the TT accelerator pedal in my 89 Corrado running an AUQ installed per this and Jimmy's guide. Randomly the pedal will stop working when driving, the engine stays running but pedal does nothing until I restart the car. I've read the fault codes and got the following:

18047 Accelerator position sensor 1/2 (G79/G185) implausible signal P1639 Intermittent

17705 Pressure drop between Turbo and Throttle valve P1297

17511 O2 Sensor Heating Bank 1 sensor 1 Performance too low P1103

17522 O2 sensor Bank 1 sensor 2 internal resistance too high P1114

17524 O2 sensor Heating Bank 1 Sensor 1 Open circuit P1116

17526 O2 sensor Heating Bank 1 sensor 2 Open circuit P1118

16622 Manifold Pressure/ Boost sensor (G31) Signal too high P0238

16490 Manifold /Air pressure = > - G71/F96 Not a plausible Signal p0106

Ross tech indicates a possible link to the lambda on that 18047 Throttle position sensor code. The pre cat lambda is fitted but not post cat. I've ordered a new pre cat lambda just to rule out anyway.
On the boost related codes I now see there's actually no MAP fitted so I assume I should have one but previous owner said it drove fine without. Could it be connected to pedal issue?
I dropped the pedal and an see no obvious damage to it or the black plug and wiring on it. The blue plug to loom is more tricky to check but nothing immediately obvious at quick look.

Any thoughts on this or guidance on what to check greatly appreciated

 

Thanks John.
So MAP ordered and on the way, new Pre cat Lambda to be fitted shortly too.
I had assumed that last code was also MAP related but see your point now.
I should have clarifed, i am also getting the codes for the known missing items such as clocks, ABS, Evap purge valve and SAI. I just left them out of this as i assumed irrelevant. I need to get them coded out at some stage.
Any suggestions on how to check continuity from the black connection on the pedal back to ecu?
Wiring is all very tight and difficult to access in around the fusebox so im suspicious of a dodgy connection.
Can the pedal switch itself be tested?
Im looking at a 8N2721503 on ebay at the moment which looks correct but im not yet convinced the pedal is dodgy :-)
Thanks as always for the fantastic support and advice!

 

Cheers John and appreciate the tip on the pedal. To be 100%, do i just pull a plug from the ecu and check basic continuity back to the 6 wires in the black connection block on the pedal or do i need certain resistance values etc? If so, will it be obvious which pins at the ecu end?

 

Hey, everyone! I'm a complete noob in wiring and harness question I had never deal with wires, I'm not an electrician, but I wanna learn that all, cuz I have dream to do a 1.8T swap with my own hands! I've read that thread a lot of times, my brain cooked something, I've got a thought that I understood how to do it, and drew a simplest scheme. I'm just not sure that I understood all right way, maybe this scheme is a complete bullshit, but at least I've tried something... Need your feedback, thanks all

Here is my scheme:
https://prnt.sc/26bezwq

 

Hi rubjonny I was wondering if you could help me, I’m currently doing a 1.8t auq conversion on a mk3 caddy, ive had it running once and revving so I decided to neaten the wiring up, went to re start and nothing(fixed the problem with new 428 relay and a better earth, now it won’t Rev, it just bogs, check pedal on comp and it shows 100% once pressed, so thinking injectors not working right? Also the blue/yellow maf wire is not connected as it cuts out if I do, hope you can help as can see you are the man

 

Hi, I used this guide last year to wire in a BDE to my vr6.. I would not have even known where to start without it, so thanks to everybody involved in it, and everyone who's added to it.

I've not used the car much since finishing the install but I'm getting p1633- 002 g185 signal too low.

So I decided to check the pedal, see if I was getting continuity etc.

To my surprise I got the same code with the pedal completely unplugged. I thought it may bring up several codes??

Anyway , I tested the plug that connects to the pedal, and I've got 2 grounds, pin 3 and 5 I think. Should there be 3 grounds?
I tested the 2 grounds and I'm getting 60ohm resistance is that a normal amount?

The other pins have 4.8v and a couple of 2.8/3.5v should they all be 5v?

Looked all over and can't find any info, maybe one of you guys know?

I'm not getting any codes for anything else , I've adapted the pedal several times. But still the same code comes up.

Thinking I got something crossed somewhere due to the high resistance, I tried giving the 2 grounds a direct 0ohm ground feed to the pedal. Leaving the high resistance grounds disconnected. Still the same.

Does anyone know how these Pedals work?
Are there 3 positives and 3 grounds ?
Do the grounds or the positives or both feed info to the ecu?

What kind of voltage and resistance should I be seeing?

Or am i going round in circles and just need a new pedal?

Any help appreciated

Thanks