1.9TDI 8v to 2.0TDI 16v, Manual to DSG Conversion (BLS to BKD)
I have a 2006 Caddy Life TDI that I have just converted from BLS to BKD engine and Manual to DSG gearbox. I thought I would do a quick write up of the process in case it helps someone in the future, and so that I have a reference document to jog my memory in the future :) This will just be a general outline, because if you need step by step instructions then you shouldn't be attempting it in the first place. I've worked on cars a fair bit over the years, but this was my first foray into engine conversions and wiring in a modern vehicle. My Caddy is now running without any fault codes with the BKD engine and DSG box :)
The single most important skill to have/learn is to read the ETKA wiring diagrams!
I used an Mk5 Golf 2.0tdi DSG as the donor vehicle. Almost everything from the golf is usable, with the exception of the shifter unit and fascia. I would highly recommend doing this from a donor vehicle as it contained all the parts I needed and I could go back to it if I needed extra wiring, pins, plugs etc. I paid next to nothing for a low mileage golf wreck and it's now basically free after selling a few parts off the car.
The BKD conversion is more or less pretty easy. If you can swap out an engine and understand a bit of wiring, it's a 2-3 day job. The only wiring you need to do is in the engine bay wiring harness, so that's not too complicated. The DSG is way harder from a wiring perspective because you need to take the dash out to get to the main wiring harness beneath.
Notes:
- Engine
Keep the radiator, AC, AC condenser, intercooler and all associated pipes connected to the engine. I only disconnected the coolant pipes at the bulkhead, the AC pipes at the front, and the fuel lines at the fuel filter. I took the rest of the engine out with everything still attached. In the future I would probably disconnect the AC pipes at the bulkhead instead. There are some differences in the BLS and BKD engine bay wiring. The BKD uses two 14pin plugs, whereas the BLS uses a single 14pin plug. You want to add a second 14mm plug to the caddy engine wiring and repin them both so that it matches the BKD wiring. That way you can don't have to do any wiring in the future if you need to replace the engine or engine wiring harness. The BKD also uses a vacuum block, so you need to sort out the wiring to that too.
- Gearbox
Keep the gearbox attached to the engine (unless you want to renew the flywheel). Everything from the golf just bolts up including engine mount, drive shafts, hubs (if your caddy doesn't come with 288mm brakes). Even the golf struts will work on the caddy and give the front end a nice drop in ride height. The hardest part of the whole conversion is the DSG wiring. You need to add the wiring for the mechatronics unit and the shifter. This involves splicing into the main wiring harness behind the dash, as well as running wires to the CECM and the SWCM. You also need to swap the key removal solenoid on the key barrel. I needed the caddy to be a DSG as I'm running it as a rental vehicle, however I would not bother converting to DSG unless you have a good reason.
- Shifter
The shifter and fascia are the only parts off the donor golf which do not swap over. The DSG shifter unit from the golf is way bigger and chunkier and will not fit in the Caddy console. I pulled a shifter and fascia off a 2013 2.0tdi caddy at my local wreckers and it works fine.
- Steering rack
My caddy came with electro steering already, which was handy. However it wouldn't be hard to convert a caddy to electric steering, though I'm not sure what you would do with the power steering pump. Presumably you would simply remove it and buy a different length accessory belt, but that's just me speculating. The electro-mechanical steering rack wiring harness isn't complicated, just swap it out from the donor car and follow the wiring diagrams.
- ECU
The ecu needs to be swapped. It has almost identical pins to the BLS ecu. You do need to add a couple of wires though. This is because the BLS motor uses a separate boost solenoid, whereas the BKD uses a vacuum block.
- Instrument cluster PCB / immobiliser
The golf instrument cluster doesn't physically fit in the caddy dash. To make the immobiliser happy, you need to swap the brains of the unit over from the donor vehicle. The immobiliser is in the instrument cluster. Remove the front fascia of the instrument cluster, then unscrew and remove the main PCB with the dials and gauges on it. Behind this you'll see a smaller PCB. This smaller PCB is the brains of the unit and contains the immobiliser. You simply need to swap this into your caddy cluster. Then swap the immobiliser chips over in your ignition keys and it will all work nicely. Note: this approach will mean that the caddy now shows the mileage and VIN from the donor vehicle. If this is an issue, then you would need to go about the immobiliser issue in another way.
- Steering wheel, SWCM, slip ring
Standard MFSW swap.
ABS
- The ABS unit is the only part I kept from my caddy. It's a MK70 unit. There is a jumper wire in the vehicle plug that tells the ABS unit what kind of car it's installed in. You need to change the jumper wire to tell it it's a golf, and then put the corresponding coding into VCDS.
Hopefully this helps someone attempting or thinking about attempting a similar conversion. It probably doesn't make much sense at first glance, but it should help you once you get into the nitty gritty of the conversion.
Let me know if anyone has any questions.
