This was posted on the ukmkivs forum by
Foxy so i thought i would share it with all the cool members on here to hopefully help someone
Due to a recent ball-achingly tedious saga of trying to get my ECU and cluster swapped, I though i'd share the information I've learned.
It's a frequent topic of discussion and to be honest, there's alot of poor infomation about it.
I'm going to tell you what I know.............
The nub of the problem is that there are (so far) two main types of immobiliser fitted to the Mk5 Golf and Jetta
........I know this situation relates to other VAG parallel marques/models but you wont believe how inconsistent VAG have been with rolling out their technology across the ranges, so I won't try and draw and comparisons here.
Right, for all those who already know about the basics, by all means skip down the page........
KEYSThere are three main parts to your key (assuming "flip" style).
1 - the mechanical metal blade..........this is cut to match your lock barrels in the doors and steering column
It's a flat piece of metal which can be removed from the flip mechanism by removing a small pin.
2 - the radio remote control.........this is paired up with your CCM (central convenience module).
It opens your doors and boot/tailgate remotely....it's a part of your key fob which can be pulled apart from the flip "nose" end.
3 - the immobiliser transponder chip........this little glass pill is in the "nose" end of your fob body, right next to the flip key mechanism.
It is read by your car's instrument cluster by inductive signal via a pick-up "ring" mounted on the ignition barrel lock.
It needs no external power, and is very fragile. Breaking the glass vial will usually brick the internals.
Do not confuse the coding of the immobiliser transponder chip with the pairing of the radio remote control.........they are totally different.
INSTRUMENT CLUSTERThe instrument cluster displays crucial information about the engine, lighting, safety systems and also such things as fuel levels, trip computer etc.
The instrument cluster houses a non-volatile memory which keeps information such as the immobiliser code (referred to as SKC or PIN).
It also knows and displays the mileage (odometer) and the car VIN number (chassis / identity).
There are various types of cluster.
The obvious differences are apparent from looking at the dials.......for example:
Petrol / Diesel versions have different RPM "red-line" figures on the techo>
Some dials have higher speed range than others>
Continental versions are in KMH not MPH>
The centre display is either midline or highline - the former has half-height red LED display; the latter has full-height>
Special versions> GTi and R32 and R-Line have different overlays and surround>
There are various manufacturers of the cluster (they might look the same but are not)
The less obvious differences are;-
Immobiliser type........2004-2006MY have "Immo 4" type, and 2007MY onward have "Immo 4c".
The "c" stands for "crypto" ( a Siemens Security technology) which is more advanced that the basic type 4 version.
How to tell if your cluster is Immo4 or Immo4c.......
Look at the left hand tacho dial and turn your ignition key to position 1........if you see a little key icon with a car outline around it.......it's Immo4.
If you put just the flat key blade in the ignition and turn it, you will activate the immobiliser.........if you see "SAFE" where the mileage is usually displayed.......it's Immo4c.
Always check YOUR part number, and know the date of manufacture of your car.
You will likely fail to match up replacements if they are not compatible.
You will definately fail if you mismatch immobiliser types.
ECUThe ECU controls the function of the engine including all aspects of combustion and fuel / air control, measurements and data acquisition from the various sensors and controls.
For each different type of engine there will be a different ECU. Some ECUs appear the same externally ie are the same type ie EDC16, but the internal software could and is likely to be totally different.
The ECU houses a non-volatile memory which keeps information such as the immobiliser code (referred to as SKC or PIN).
It also knows and displays the mileage (called "secret mileage") and the car VIN number (chassis / identity).
Always check YOUR part number INCLUDING the last couple of digits which will be letters, and know the date of manufacture of your car.
You will likely fail to match up replacements if they are not compatible.
You will definately fail if you mismatch immobiliser types.
Firstly, let's talk about MY2004 - 2006 Golf/Jetta
You "should" be able to find out the immobiliser SKC / PIN by looking at the plastic tag which was supplied with the car keys from new.
This should be a 5-digit code. Do not confuse this code with the 4-digit radio code often listed on the fob too.
This will give you access to the immobiliser and allow you to carry out "secure" functions with vag-com (VCDS).
If you cannot locate the SKC / PIN in this way, you should be able to determine it using one of the many clones of "VAG-COMMANDER" lead and software on the market.
Some are very cheap and be aware they are less reliable. The hardware in the £100-200 range should work well, unless you want to invest £4-7k in the full genuine vag-commander system!
You can log into the cluster or the ECU to achieve this information.
KeysIf you need a new key and have one already, you can have another key made at most good locksmiths.
Be aware that if you buy a so called "new" key from eBay, be sure it is absolutely new and unused.
The transponder chips must be "virgin" and can only be programmed once!!!
The blade is easy enough to have cut from your other one as a template.
The radio remote can be any new or used one, provided it's the same radio "frequency" (check the part number carefully and the frequency written next to that inside the unit).
If you order a "new" key from the dealer, they will need the vehicle VIN number and some personal ID.
The new key will come complete and the blade pre-cut to your locks (the vehicle identity).
It will have a virgin trasponder chip which will still need coding to your car at extra cost.
The radio remote will need pairing to your car (see the car user manual for this procedure).
Instrument Cluster SwappingIf you can locate a used cluster of same type, year, manufacturer, and have the SKC code for them, you should be able to swap them using VCDS (vag-com).
This is a common procedure and generally followed if you want, for example, to upgrade your car to a "full FIS" display.
Provided the part numbers are identical except the penultimate numeric digit then you should be successful.
(This digit is different and distinguishes half height from full height FIS types).
You can buy a new "virgin" cluster from the dealer, and you can then do the swap a bit easier, as there is no "used" cluster SKC to deal with.
The dealer will usually sell on an exchange basis or levvy a surcharge. The exchange must be for identical part number.
Using VCDS- it will tell the new/used cluster to "pull" the vehicle mileage, VIN number and immobiliser details off the ECU.
VCDS has set procedures for this. Check Ross-Tech Wiki if unsure.
Once complete, the new/used cluster will be programmed to the identical data of your original.
You may need to check stored TDCs (fault codes), go through basic coding it to suit your features of the car, and do adaptation of steering angle sensor, abs braking etc.
VCDS had set procedures for this. Check Ross-Tech Wiki if unsure.
All your existing keys will remain usable and no other coding or matching is required.
ECU SwappingIf you can locate a used ECU of same type, year, manufacturer, and have the SKC code for it, you should be able to swap it using VCDS (vag-com).
Provided the part numbers are identical then you should be successful.
You can buy a new "virgin" ECU from the dealer, and you can then do the swap a bit easier, as there is no "used" ECU SKC to deal with.
The dealer will usually sell on an exchange basis or levvy a surcharge. The exchange must be for identical part number.
Using VCDS - it will tell the new/used ECU to "pull" the vehicle mileage, VIN number and immobiliser details off the instrument cluster.
VCDS has set procedures for this. Check Ross-Tech Wiki if unsure.
Once complete, the new/used ECU will be programmed to the identical data of your original.
You may need to check stored TDCs (fault codes), go through adaptation eg EGR, etc.
VCDS has set procedures for this. Check Ross-Tech Wiki if unsure.
All your existing keys will remain usable and no other coding or matching is required.
Secondly, let's talk about
MY2007 -> Golf/JettaVW (in their infinite wisdom), have deployed the Siemens "crypto" version of the Immo4.
The technology is apparently employed in the instrument cluster and the immobiliser transponder chip.
The ECU seems not to have Immo4c protection and hence is less secure in it's own right, however it must still conform to all the parameters which need to be agreed between that, the cluster and the key before it will allow the vehicle to run properly.
VW have changed the way they deal with SKC/PIN codes too.
The codes are now kept in a secure database in Germany called "GeKo".
It keeps all vehicle identities (using VIN) and then all the lock suiting and SKC data.
If you visit your local dealer and ask for your SKC code, you WILL NOT GET IT.
(when the dealer has to follow secure procedures such as key coding, even they do not ever get to see the SKC code........it is transferred the VAS tool discretely over the data network)
The newer type SKC codes (depending on usage) are 7-digit, and are in fact encrypted versions of the 5-digit code which are calculated using the dealer number and the date and time the SKC was retrieved!!
Ross-tech have confirmed to me personally this week, that their software does not support any of the key coding / cluster swapping / ECU swapping procedures under Immo4c equipped vehicles.
They claim this is due to the now unlikelihood of anyone being able to get the SKC codes. This is rather annoying to say the least.........
I can confirm from experience that the SKC can be retrieved relatively easily using inexpensive VAG-COMMANDER type hardware, direct from the ECU. (but NOT the cluster.......however, it is the same code!)
KeysIf you need a new key and have one already, you can have another key made but you will need to order it and have it coded at the dealer.
The flip key is no different to earlier ones, except the transponder chip.
The transponder chips for Immo4c now arrive "part pre-coded" with your VIN.
The new key will come complete and the blade pre-cut to your locks (the vehicle identity).
[ The blade is easy enough to have cut from your other one as a template, if that's all you needed.
The radio remote can be any new or used one, provided it's the same radio "frequency" (check the part number carefully and the frequency written next to that inside the unit). ]
When you order a "new" key from the dealer, they will need the vehicle VIN number and some personal ID.
The radio remote will need pairing to your car (see the car user manual for this procedure).
If you lose all your car keys, be prepared for an expensive bill;-
VW will automatically need to give your car a new "identity"......which may also entail new lock barrels.
Your car will need to be taken to the dealership to have the new key(s) coded to your ECU and clocks.
Instrument Cluster SwappingYou cannot currently achieve this with VCDS.
My dealer contact told me that they had tried this once and made a hash of it, so would not be offering it again. They would only do new cluster swaps.
The dealer will usually sell a new virgin cluster on an exchange basis or levvy a surcharge. The exchange must be for identical part number.
All your existing keys will remain usable and no other coding or matching is required.
ECU SwappingYou cannot currently achieve this with VCDS.
My dealer contact told me that they had tried this once and made a hash of it, so would not be offering it again. They would only do new ECU swaps.
The dealer will usually sell a new virgin ECU on an exchange basis or levvy a surcharge. The exchange must be for identical part number.
All your existing keys will remain usable and no other coding or matching is required.
OK, so what about WORK AROUNDS?
KEYSThere are no easy work arounds...........so just don't lose 'em !!!
I have read that some of the better locksmiths *may* be able to order you a transponder chip part-pre programmed, however this is kinda sketchy information.
I spoke to "Eydens" in Coventry and they said it "should" be possible.............hmmmm....I'm not filled with confidence.
INSTRUMENT CLUSTERWell this is the second toughest part due to the Immo lock-down.
The Mk5 clusters have a small circuit board in the back of the unit which appears to have the "brains".
This plugs into a fascia "display" board which seems to do the display processing and of course has the dials etc.
I have yet to verify this (and I'm going to try it imminently), but I believe if you plug a compatible FULL FIS fascia PCB into your original HALF FIS rear PCB, it *might* work ok.
Other work-arounds involve "cloning" the data from the Immo chip and other flash memory chips from your original cluster onto the donor cluster....this is untried AFAIK and again may not be possible due to the pesky Immo.
Another more certain work-around is to swap all the main chips physically to the donor cluster....again, I've not read/heard of this being 100% viable for sure.
ECUThis is probably the easiest part to work-around.
Due to the apparent lower level of security, the ECU is relatively easy to clone.
Most good remapping companies will have the hardware, software and knowledge to accomplish this.
They will read the original ECU memory including immobiliser (hence SKC / mileage and VIN), and copy it onto the donor ECU.
The actual exact donor ECU part number might not be hyper-critical, provided it is for the same ENGINE CODE, it should be possible to clone it.
Another short-term alternative for sorting out a faulty ECU and to "get you going".......get a donor ECU (again provided it's for your engine code, it should be ok), and have the immobiliser bypassed.
Again, the good remapping companies should be able to do this for you at relatively small cost.
Your car will run fine provided it was only and internal ECU issue previously......of course the stored VIN,and mileage will be incorrect but it might get you out of a difficult spot.
[ I have tried this and I can run my car without ANY clocks present, provided I have the right mechanical key blade. The ECU never questions the cluster for it's Immobiliser status, hence will run no matter what]
I hope this is useful and answers what seems to be pretty common questions.
Massive thanks to Foxy for this info
