GolfGTIforum.co.uk
Model specific boards => Golf mk3 => Topic started by: mark-mk3gti on 13 October 2010, 13:02
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hi all, being trying for ages to get vagcom to read ecu, it used to, but now will not, what ever i try i can always read abs module but rarely now not at all the ecu
i purchased a hand scanner which works fine with abs, but says error when connecting to ecu,
i can hear clicks behind clocks but fails.
bein having the cut out while drive issue for a while and yesterday replaced the crank sensor, which was cream crackered, when i got it out had a look at cable which looked finebut when messed with it a little bit it fell apart in my hand, dont think it was shorting but definately brittle cables and generally looked crap.
just gonna have a look at ecu and see if i can clean pins up or somet, but anyone got any idea why it would stop reading? is ecu fubared?
any help apreciated, btw its a 96 gti 8v 125k agg engine
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What version of VAG com are you using? later ones are better.
The ECU could be at fault itself.
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I've tried all of em, but originally 409.1 worked with eBay lead, but now doesn't, hand scanner is the correct one and can read abs, just cleaning pins on ecu now, but didn't work, so giving it another go and checking loom as best as I can, but yeah doesn't look good for ecu I guess :(
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nothign wrong with vag-com if the other scanner cant see ecu either.
look behind fusebox for any grey/white wires, there should be one from ecu to a plug on the immobiliser control unit. try vag-com again ands see if you can connect to the immobiliser, if not then the unit has packed in. if you can that suggests the problem is the comms between the immob unit and the ecu. it is also possible for the immob boxes to fail in such a way they still power up and communicate with vag-com, but they wont communicate with the ecu. this will lead to immobiliser issues.
the clicking noise you can hear is the immob box, this means the immobiliser box does at least have power, and it can see that you are trying to communicate with the ecu
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Hi, thanks for help, just tried to connect with immob but no joy, slowed baud rates down in case and still doesn't, but does abs. Just noticed am running ftdi drivers for port, that ok? I've tried a few.. Lol
Car starts and runs but have being having the cut out problem, crank sensor was knackered so replaced, but now I am wondering if immob box is the prob, is there anyway of removing it so everything works normally? Ie vagcom as car does have another Alarm onnit, can the immob box be changed easily? Guess it needs recoding aswell! Sounds like fun!!
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Had a look for wires but couldn't spot them, it's a jungle and only had small torch, think i can see the immob box, is it up to the left of the column? Looks like it's silver with couple of plugs on it?
Think it's gone above my head electronically, am not sure what's best to do now? I'll know if it runs right now after a few work runs as that's when it happens the most, but this vagcom fault code reader thing is bugging me a lot.. I like everything working as it shud, where to go now?
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if the car runs the immob box can communicate with the ecu ok, unless you mean it fires up for a couple seconds then cuts out? thats immob fault symptom. if car runs for a whiel and cuts out at junctions then its nothing to do with the immob.
if you look above the fusebox near the column you'll hopefully spot the immob box. its black and a little smaller than a pack of cigarettes. its well hidden in a mk3 dash, proper mare to get to! follow the wire from the transponder ring and hopefully you'll spot it. then there are 2 grey or grey/white wires, 1 runs to the diagnostics jumper block above the fusebox the other connects to the ecu diagnostics wire with a brown plug
(http://vwtech.no-ip.info/images/golf/diagnostics2.jpg)
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Hi mate, yeah I saw that box! Looks like fun to get out! :)
Take it u disconnected yours then?
Yeah the prob was revs dropping at speed and on one occassion when at lights, just changed crank sensor as it was knackered and also realised I had cyl 3 n 4 firing wrong way round for several months :embarassed:
Just wanted to read codes off car, if u reckon immob box is causing it is it just a matter of disconnecting it from car?
Sorry if I'm seeming a bit dumb just wanna get it right as this my daily!!
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nah i put one in, abf swap into mk2 golf ;)
wasnt fun ripping that loom out in one piece from the donor mk3 i can tell you! you cant just pull the immob box either, to bypass it you have to send the ecu off to have the immob defeated.
as i say, if the immob is the problem you can get one from any other mk3 golfy just as long as it also comes with a matched chip. once you fit the matched box and chip to your car/key, you then use vag-com to code your ecu to them.
to match new keys to the immob box you need the skc code, and you can only get the skc code if there is a matched key in the ignition. i.e. random immob boxes on their own nicked from the scrappy are as good as scrap without the key to match!
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hi john,
sounds like fun, lol, shame there is no way of proving its the immob box, although i guess i could get one with a key/chip and swap boxes and see if vagcom connects to them both? would that work? would it allow me to connect even if immob not coded to ecu or vica-versa?
then if it does connect to ecu and immob then i can code everything up.. hopefuly
what would u do?
i just dont understand how i can always connect to abs module first time no problems but nothing else, i wuld of thought abs went through imob aswell as i am sure it clicks the same aswell
hopefully crank sensor solves my problems with rpm drops, will no over weekend after work runs.. :)
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i would start looking at the jumper box above the fusebox, i recon issue is between that and the immob box, or from there to the diagnostics plug. since the car will drive a bit before cutting out the box and ecu communications are ok. if the wiring is definitly ok, then there must be a problem with the box itself which is preventing it from communicating with vag-com even though it can still talk to the ecu.
any old immob box will plug into the loom and communicate with vag-com, it will also let you talk to the ecu. just the car wont start due to immob missmatch, and if you dont get one with a matched key chip you cant match it to the ecu
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hi mate, thanks for your help, car seems to be running pretty good after crank sensor, hasnt done the cut out thing (touching wood)
gonna have another look at alarm stuff ontop of fuse box when im next off now, towards end of next week.
i dont think the immob is faulty as such, just annoying i cant read codes off ecu at mo, but hopefully its a loose cable to diag socket.. will post again when tried again..
thanks again
mark
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if the car runs the immob box can communicate with the ecu ok, unless you mean it fires up for a couple seconds then cuts out? thats immob fault symptom. if car runs for a whiel and cuts out at junctions then its nothing to do with the immob.
if you look above the fusebox near the column you'll hopefully spot the immob box. its black and a little smaller than a pack of cigarettes. its well hidden in a mk3 dash, proper mare to get to! follow the wire from the transponder ring and hopefully you'll spot it. then there are 2 grey or grey/white wires, 1 runs to the diagnostics jumper block above the fusebox the other connects to the ecu diagnostics wire with a brown plug
(http://vwtech.no-ip.info/images/golf/diagnostics2.jpg)
hi mate, i never really did anything bout this issue, but was a bit bored for an hour so went to have a look, car runs perfectly after crank sensor (touch wood no ive prob cursed it) and bein looking into vagcom fault again, still cant read ecu and as it turns out the immob, but can always read abs module, so does this point to immob box fault?
(http://i870.photobucket.com/albums/ab269/mark3gti/Golf%20Mk3%20GTI%208v/38218eba.jpg)
i havent pulled it all apart but have had a look and have seen the box on fusebox and can see immob box no prob, only thing i havent seen is that brown plug, have checked grey/white wire is present at diag socket, and there are a few in this rail thing on fb, that brown plug, from what you said it runs onto ecu? if it was d/c would car run ok? but diags not connect?
there is no mad rush to get things going but i may need diags one day..
what would u do? guess i need to locate that brown plug and check it is connected ok? or am i gonna need to pick up a immob box with a key?
cheers for your help..
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aha. see that wire on the far right? move it to the top row. its on the bottom row, which is the wrong place. see all the other grey & grey/white wires are on the top row?
top row and bottom row are separate circuits :)
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just gonna try now, brb, maybe thats why it didnt always connect? when i first got the car, and dare i ask why the hell is it in the wrong place, lol brb
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hi mate, just in car now and still no joy, it doesnt connect with handheld thing, and laptop with 409.1 or lite, so am i back to the plug? it was never gonna be that easy for me, lol,
btw still get abs ok on both...
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follow all those grey wires to where they come from, one of them should run to the immob box. check out all the other connections there and see if anything looks odd. if nothing runs to the immob box, follow the wires from it till you find the grey wire which should be connected to the jumper block and plug it in!
if it all looks ok then i would say the issue is the immob box itself. see if you can get a random one from scrappy, plug that one in and retry the diagnostics
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hi mate, ok ill have a go at some point very soon, just it bloody freezing, and cant feel my fingers again, dunno if it makes any difference but when trying to connect to immob or ecu you can hear the clicking sound from; i assume the immob box, but then it fails to connect, its an absolute jungle behind the fuse box, so will take me a while i reckon, so will have to do it on my next days off, cos i need it to get to and from work, so cant start out today,
you obviously know ur way around electrics in these things, shame you arent a bit nearer the manchester area :)
but why would it of worked at all with that wire in wrong place? it makes sense they shud be on the same row,
ill keep my ears and eyes open for an immob box and test that see what happens, in theory would all the diags then work even with the immob box not coded correctly? just read a previous post! :)
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that does suggest wire from there t oimmob box was fine, and that other wire was for something else.
sicne car runs, and immob box clicks i would say the wiring is ok, but the immob box is bust. assuming ecu is post-96 one with built in immobiliser anyway, if early one or immob has been bypassed then there doesnt need to be a diagnostics line between ecu and immob box for car to run
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hi mate, sorry im taking up ur time with this, ive got it in my head again, and would like to get sorted, so should i put that wire back?
car is a 96, registered in oct, but that doesnt help, how can i check which one i got? and what would u do next? have to say im getting confused again lol,i was just starting to get to grips then boom, lol
i went out and had another poke around, think i found most of the connectors and wires, but hard to trace as go into a loom, but think ive seen most of them now, and all look to ok, obviously im not 100% but am prob close...
i'm guessing (correct if wrong) that of my four plugs, 1 goes to diag port, 1 to abs module 1 to ecu module srs and 1 to immob, im pretty confident that brown one u had me move goes to immob, but hasnt changed anything,. and then a grey lead from immob to ecu via brown plug,
so maybe i should get a uncoded key cut and see if car runs without chip, if it does then either immob is knackered or being bypassed, but if cuts out after is it like 10secs? then immob ok?
so shud i get hold of another box and swap test see if diags come on?
initially when i got car, it did work, but took a few goes and was hit and miss, so thinking bout it could be the box,
what would you try?
i am really sorry! are you going to pod in april? need to get you a beer!! :D
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step 1, i would get another immob box out of the scrappy and plug it in, see if that helps :)
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step 1, i would get another immob box out of the scrappy and plug it in, see if that helps :)
Lol, I'll get on it! :)
Cheers for your help!
Will update when I have a immob to test..
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Good news, immob box n Key chips come today, just tried connecting it up to car and got both lappy and handheld both working perfectly straight away! So my immob box is duff, just doesn't affect running of car,
On vagcom when I log into the module before I permanently fit box, Can I test that the chips work in any way?
So I need to fit permanently now, but need to do somet on vagcom to seal the deal, I have vagcom 409.1 which is the full version so what steps do I need to take to get everything back to normal.
I did search before asking but seen I few different people mentioning different blocks etc,
If anyone fancies jotting down a quick run through for me that would be brill...
Cheers all! Will update as going on...
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this is how you code a different ecu to your new immob box, just as it says near the bottom you click 'immobiliser' rather than 'instruments' in a mk3 :)
http://www.ross-tech.com/vag-com/cars/immobilizer2.html
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hi rj, thanks for the post, just to confirm all sorted now, (touch wood) thanks for all ur help via pms.
rj-- legend! :cool:
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:cool: