must have a chip in em, otherwise you wouldnt get immobilisor faults is MY point plus all MK3s from 96 onwards got them as std!
Sorry geezer, you are right, it does have a chip (tiny wee thing about 4x10mm) in the key. Do you know how to get the transponbder ring thing off the ignition barrel? Doesn't appear too obvious to me! I checked the connectors going into the contol box under the dash and it looks ok, the board in the control module looks fine- no signs of corrosion. I'm thinking new transponder ring next, will see if I can find one in a scrappy.
Right, got the thing off and did another vagcom check, it then reported a problem with the ignition ring. I'm now thinking the problem lies elsewhere as this doesn't happen when it's connected. It is constant now with the "data wiring faulty 27-00 implausible signal". Tried clearing several times and it just keeps coming back. Until this is cleared the engine is locked down. I'm stuck now, where else can I check? Anyone know where the wires (apart from the earth & ignition ring ones) go to? I'm guessing they all go to the ecu?
the diagnostic wire comes out of the ecu, goes into the immobilisor box then out to the vag-com port, I'd say either the ring or box is faulty, or the ecu has lost the key coding.
I don't think it's the immobiliser box, that module is reading fine. I checked continuity on the data wire between the comms port and the ecu and it was fine. The fact that the engine module isn't being read any more leads me to believe it's a problem with the ecu itself, gonna try changing the ecu relay and see if that does anything.
iirc the modules are known for failing and preventing proper communication with the ecu? might be wrong on that one...
Looks like i have a similar problem http://www.clubgti.com/forum/showthread.php?t=171777 but on a MK1 16V on K-jet
If that's the case can you get a replacement box, and is it costly? Presumably I'd need to replace the chips in the keys and re-program the ecu too.
a second hand one should be ok, and afaik you can swap it no problem, the coding is with the ecu not the transponder box (I think)
Changed the ecu relay and, hey presto fuel primed and engine module reads again, all codes are gone- including the immobiliser one. Sat for a minute of sweating and turned the key- no joy! cranked away again. Fiddlesticks! Gonna try TB re-alignment next, see if that does anything.
I dont know if the AGG has one, but my mates ABF has a vac line from the throttle/inlet area to to the ECU. shortly after the swap it got sawn thru by a heat shield and casued the same issue?
If anyone else is interested, I had a word with the parts guy at verve glasgow just in case the ecu relay wasn't the issue. He said a new immobiliser control box would be 130 + VAT fitted, it and your keys need to be re-coded apparently. A new ecu is 650 + vat + fitting and programing (cough) Luckily it doesn't look like that's it for me. (yet)
I don't know if it has one either, Got any pics? I haven't seen any obviously damaged lines around the throttle area.
well basically if you find the ecu (under the plastic scuttle panel top o engine bay, see if it has a vacuum line to it, if it does follow it all the way to the other end, l;ookign for any damage
I tried to do the TBA by doing this: etc. got nowhere with it. 098 came up with nothing so I tried 001 and it gave some readings, one of which was "coolant temp -7C" which I thought rather odd given that it's probably about 20C outside just now. Could a bad coolant temp sensor be a non-starter? Is there a way to test it? I also noticed that the oil light keeps flashing for a bit after I stop cranking it over. Oil level is fine and I changed it a couple of months ago.
ok cool, yeah the ecu temp sensor is deffo worth swapping, in fact I don't know why I didnt say to do that ages ago
