So me and some friends have decided to try and put a 1.8t AUM into my Mk3 Cabrio. Have managed to source the hardware and ready to roll but a bit stuck on the wiring for the engine loom. I've tried to find a information but a quick google always points to doing the conversion in a Mk2. Has anyone got a good guide for splicing that would help or does anyone know if RubJohnny is still out there as I've seen his name mentioned a few times. Thanks
this is the guide you are looking for http://www.clubgti.com/showthread.php?267196 I still do looms just my waiting list is quite long unfortunately. Chris Bellman or James E looms on facebook do good work
Hi rubjonny, I'm new here but I am doing the conversion in this thread with 18tCabrio Your guide is awesome but can I ask a quick question . Our loom (2003 1.8t AUM) does have slightly different coloured wires they actually match the original wiring guide thread. I presume this doesn't matter and the important thing is the pin locations? Thanks !
Awesome mate! Followed the guide yesterday and everything(ish) seems fine. Few niggles: Hazard light on the switch stays on and indicators don't work Temperature gauge and fuel gauge bounce up and down when ignition isn't on Electric hood doesn't work, this may be an issue because the brake switch isn't in place yet I also have two small wires coming from the fan control module which I don't know where they go. Its a non air con controller so only one connecter. Any ideas mate? I'm thinking a bad ground somewhere Cheers
as in hazard switch is stuck down? might need a wiggle, check the plugs all seated correctly check g1/5 is earthed hood needs key in ignition live from the grey parking light switch, again make sure all plugs fully seated pics?
Thanks for the reply No the hazard switch isn't stuck down it just stays on and doesn't flash when you press it. Ill try that ground thanks Yeah I think the hood will be an easy fix The fan control module is the same as the one here https://www.ebay.co.uk/itm/401286565778 Thanks Tom
The wires are 1: red - perm live 2: brown/black - ? 3:red white - to fan and thermo switch 4: brown - earth? 5: empty 6:black yellow - ? Cheers Tom
brown is earth aye, brown/black goes to the rad fan after-run thermoswitch, and yellow/black needs ignition live. it would run to one of the jumpers above the fusebox originally
Legend ! Thanks so much ! I think I'll bin off the after-run. Looking at the other issues tomorrow. Hopefully grounding g1/5 will sort the cluster issue . Also noticed that nothing is displayed on the LCD screens . No clock / mileage etc. Maybe linked ?
Cluster issues all went away when I grounded g1/5 ! Thanks for that Fan all sorted ! Binned off the after run Electric hood isn't working because P at the ignition switch isn't going live in any key position. I think il have to change the entire stalk/ignition switch to fix the hazard issue too.
yeah pin P should be live with ignition off, if it isnt then your switch is bust. peeps often re-jig the wiring anyway so the hood will work with the ignition on, only other thing that runs off P is the parking lights system which most folk dont use or even know about
Fixed the hazard issue , it was a bad relay The issue with the hood was because P in the ignition barrel was bent flat and not going into the plug ! Straightened her out and all works fine. Thanks for all your help ! Much appreciated buddy
Rj Quick one, I've finished wiring up the motor completely now, everything on the MFA cluster works as it's supposed too. When the engine (1.8t AUM) is warm (oil temperature on MFA says about 70) the low pressure oil light comes on. Now I'm presuming this isn't related to wiring and is probably something engine wise. I believe the mk3 cluster will buzz if it's high pressure ?. I'm using the blue oil pressure sensor from a mk3 for low . White sensor from a nk3 for high and a tpiece and mk3 temp sensor for the mfa . Is that correct ? Tom
that all sounds correct, where have you put the switches? Some cheaper T pieces are not quite deep enough and the sensor can bottom out inside the casting blockign oil flow to the other one in there if you disconnect the blue/black wire the light shoudl go off, if it does then you know wirign is all ok you have a sensor issue or oil pressure really is low.
The low pressure sensor is in the oil filter housing , the high pressure and mfa sensor is in a tpiece. I thought the low sensor only did anything under 1800-2000 rpm ? Once mine comes on it's on all the time. I've just got a genuine sensor from TPS to see if it's a duff sensor and also a pressure gauge to check. I did notice that In vagcom measuring block 92 (maybe 93) that the Valve Adjustment status nearly always shows off, no matter what rpm or engine load. On a separate note, your guide says to leave the brake pedal sensor cable dangling by the fuse box. I did this (it's just lying near the ecu in the scuttle) and noticed on Vagcom in the measuring blocks that the "Brake Switch" will always say "Activated" which makes sense . However, I'm just wondering if this may impact performance as I've read that the ecu does something to cut boost (maybe via one of the vacuum valves) when it sees the brakes have been applied (maybe to stop left foot braking) .
yeah iirc if the oil warning is triggered on these it will stay on, but not 100%. yes the low pressure will trigger if pressure drops below 0.24/0.3bar at idle, its an 'earth to trigger' contact on this one so if you disconnect the spade the oil light should never go on. this will tell you if the wire is shorting in the harness somewhere and triggering the light. if the light stays off then you know either the switch is bad or you really do have low oil pressure with the clutch and brake switch at the time of writing I had no concrete info if either of the switches were required or not, so to be safe I suggested you should run the wires then you can add them later if need be. the clutch switch apparently will cause the revs to hang between gears if missing, but still not heard anything 100% either way on the brake switch. It is definitely required if you wanted cruise control, or launch control later on. if you suspect the switch is an issue then its easy enough to add, grab yourself a mk4 plug for starters. tap the mk4 switch and ecu red/black wires to the old mk3 red/black. the mk4 brown/red to mk3 red/yellow, join the switch & ecu yellow/white wires and finally give the black/blue an ignition live (g2/4 is ideal) job done. Try to get the later type brake switch as its much easier to fit without messing up, part number 1C0945511A RDW
You need to have the brake switch connected and functional with pedal movements. That is all I would say.
