Replacing an ECU without having to recode....which parts have to be replaced? VW Caddy TDI van

ECU box is giving trouble and when I went to get a new (used) one from a scrapyard they told me that if i got the key, ignition ring, and dashboard control panel (with speedometer etc) along with the ECU from an old van and swopped all those into my van, that i then wouldnt have to take the van to VW dealer to have it recoded. My mechanic replaced all those things (though he doesnt think the dashboard matters), and it still isnt reading the code…we know the ECU is working because the van will start, but then shuts down after a few seconds. I asked the scrapyard guy again and he said as far as hes aware those are the parts that are needed to swop out in order to not have to recode. I double checked that he had sent us the correct key and he said he had. Are there any other parts that we need from the old van to put into my van to avoid having to go have it recoded at VW?
(in the meantime, he opened up my box and cleaned the corrosion and got the van running, but suspects the ECU is still trouble and I’ve still got the glow plugs light flashing).

The van is a 2003 VW Caddy van, diesel, TDI. steering wheel on right side.


What makes you think having the dealer “recode” the scrapyard ECU will make any difference.??

Most mechanics have learned that this kind of computer/black box problem is simply not field repairable…You can’t just go swapping this stuff around and expect things to work…The parts must be THE EXACT ones specified for your model vehicle. The DEALER will order those parts based on your vans VIN…Will that cure your problem? No guarantee! Sorry, electrical parts can not be returned…

A good old-time mechanic should be able to reconfigure the vans engine so it will operate with NO electronic controls. Of course, the COST of doing any of this may greatly exceed the value of the vehicle…

Is there any reason why going to the dealer for a ‘recode’ is so bad? I had a friend with a Cadillac that had the chip in the key fall out and get lost. The car refused to start after that, and only flashed the ‘security’ light. Since it was the only key he had, the car was towed to the Caddy dealer where they cut a new key with chip using the old key, then recoded the key for the security system. Had him back and running in less than an hour.

A quick google search lead me to a site that describes the immobilizer system in your van. There are two things required to recode the security system which may have a separate ‘brain box’ from the ECU. The first is the SKC (secret key code) which is required to access the immobilizer functions through the scan tool. This is available only from the dealer, and requires the VIN number and proof of ownership to retrieve it. The other is a VW specific scan tool. The dealer has one, but there are others available, like the Ross Tech VAG COM. They are not cheap, so knowing someone like a VW or Audi mechanic who would invest in one would be very helpful.