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Discussion Starter #1
Just recently bought t4 .2.5 tdi have had a full service on it done two trips to Carlisle and back and never missed a beat also local runs as well. Went out to it the other night and instead of using the normal key i use i used the spare and all it does now is starts and then cuts out after a few seconds. I've tried taking the battery of and charging it to see if it resets the immobiliser to no avail, I've tried using the normal key i used same thing happens. Is there anyone local to cannock with a vag com that could help me out ????
 

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Discussion Starter #3
Hello and sorry i should of introduced myself I'm Dave new to the T4 scene I've recently acquired one and planning on converting it but have already encountered a problem with the engine refer to previous posting.
 

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If it's turning over and starting, then dying more or less immediately, it means that the immobiliser is doing its job properly!

The key fob contains a transponder chip which matches to the immobiliser unit behind the clocks. When you insert the key and turn it, the immobiliser fires a relay which starts the fuel pump, allowing the engine to run.

So, your possible issues are one or a combination of the following -

1. Transponder chips in both keys not working (unlikely that both would go at the same time, unless they've both been subjected to a huge blast of static or been in a very strong magnetic field)
2. Immobiliser unit not recognising the keys.
3. Relay at the fuel pump stuck open, or not receiving a voltage from the immobiliser to close the circuit - think bad connection, damaged wire, etc.

It is possible to over-ride the immobiliser by supplying a permanent 12v feed from the ignition switch to fuel pump relay so that the pump is energised as soon as you turn the key, regardless of whether the keys are talking to the immobiliser or not.
 

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I had something similar, one of my keys stopped being recognised by the immobiliser, fortunately my other key was ok, so I took them both to Timpsons and they stuck them in their little machine, they were both programmed but one was dodgy so they gave me a new chip and programmed it for me.

Cost about 30 quid.

R
 

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Discussion Starter #9
Thanks for the info will be trying them all. Will let you know the outcome. Thanks all i miss me van.
 

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Discussion Starter #10
Hi, all not sorted out yet as when I tried 1 of the suggestions the battery died so on charge at moment. And the fact that it's pi##ing it down doesn't help matters. Will update soon.
 

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Discussion Starter #12
Hi, all . Checked immobiliser fuse and seems to be intact also checked fuel pump fuse as well while I was there. Also been to local key cutters and the chap i needed to see was out on a job so in limbo at the moment. Going to VW tomorrow to get me car done as it's got one of those dodgy emissions chips in so while I'm there I'll ask them.
 

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Discussion Starter #13
Re: t4 transporter 2.5 tdi 2002 CANNOCK.

Hi, all , still no joy yet but will be on it first thing as I'm missing it and the fact that it was only mot,ed 2 weeks ago is twisting me melon man.
 

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Discussion Starter #15
Hi, not at the moment going for new key tomorrow £40 if that doesn't work it will mean garage job unless any other members on here are a mechanic and could have a look ?? What's yours doing mate ??
 

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Discussion Starter #16
Hi , I'm sorry i haven't posted anything but I've been in a deep state of depression after putting my keys somewhere safe and forgetting where I've put them. I've been searching all week to no avail I've found other things that I have mislaid but not the keys to the HOLY GRAIL:*
 

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You say that you've checked the immobiliser and fuel pump fuses. Have you actually tested them, or just done a visual inspection? Have you tried swapping them out for known good ones or putting a continuity tester across them?

Even if the fuses are good, there's no guaranteeing that either the immobiliser or fuel pump are good, but if the pump was stuck then it should blow the fuse - that's what it's there for after all!!

There's also the possibility that there could be a blockage in one or more fuel lines (dirt) - possibly caused by a dirty/contaminated fuel filter, or an air lock in fuel lines. It could even be lack of compression, as obviously diesel engines rely on compression for combustion - the valves could be badly worn, you could have a holed piston, cracked liner, damaged or missing rings, damaged head gasket...there's any number of possibilities :eek:

My money's still on the key/immobiliser handshake though. I'd say that your next step is to connect a switched +12V from the ignition switch to the fuel pump - you can jury-rig this temporarily to try it, if it starts and runs with this in place then then you know that the key isn't talking to the immobiliser.
 

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Discussion Starter #18
Cheers for that information but how do I go about doing the temporary wire to the pump bit as I haven't got a clue what to do ?? :* Many thanks T:
 

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Discussion Starter #20
Hi, there what does yours actually do ?? I've not actually touched it for a while due to other commitments but desperately needs to be sorted. Yours looks good nice one and enjoy. T:
 
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