- 2007 VW Passat Engine Swap - 2.5L for 2.0T
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    1. Member
      Join Date
      Jul 7th, 2009
      Thunder Bay, Canada
      2003 TDI Jetta Wagon, 2004 Golf R32
      02-07-2017 01:03 PM #26
      I used ELSAWin to get the diagrams. Give me the Engine Codes and VINs of the cars you are using and I can get the correct wiring diagrams.

    2. 02-08-2017 08:56 AM #27
      Dorkage, the VIN number of my 2007 VW Passat is: WVWLK73C97E009332 ... the engine code for the original 2.0T engine is: BPY. I'll have to see if I can get the VIN number for the 2008 Jetta that the ECU and/or engine came out of ... but the engine code for the Jetta 2.5L is: CBU.

      Low_passat had emailed me a PDF wiring diagram for the 2007 Passat 2.0T ... and I've already got all of the chassis ECU pin locations / colors ... and I've verified that they do correspond with my car ... so I've got that.

      I really just need the diagrams for the 2008 2.5 Jetta.

      I'm supposed to get my Bentley Manual today.

    3. 02-19-2017 05:40 PM #28
      Well, I'm about ready to get back to this project. I've got all the wiring diagrams that I need ... it's just a matter of sorting them out and matching up the wires ... on paper first. I discovered (from the Bentley Manual) that I DO in fact have the T121 plug on the 2008 Jetta ECU.

      All the VW ECU's have two plugs ... a chassis wiring harness plug, and an engine wiring harness plug. On the 2007 Passat ... the chassis plug is a 94-pin plug, hence it's labeled T94 ... the engine wiring harness plug is a 60-pin plug, hence it's labeled T60. But the smaller plugs on the 2008-09 Jetta they label ALL as T121 ... with 121 pins COMBINED for both chassis side and engine side. The chassis harness side consists of pins 1 through 81 ... the engine harness side consists of pins 82 through 121.

      While I've had to work on other projects lately, I've had time to sort out the wiring on paper at home. I also sent my ECU off to have the immobilizer disabled ... they did it the same day the received it, and sent it back to me.

      The company from eBay that did the ECU work is VARParts and they specialize in VW / Audi custom parts, servicing, and restoration. Not sure where they're located, but their phone number is:857-540-5060.

      I hope to get back to the wiring by the end of this week or next ... I'll keep you posted.

    4. 03-20-2017 08:47 PM #29
      Well, I'm finally (REALLY) getting back to this project. After a Hyundai Tiburon engine replacement and a Saturn VUE transmission replacement.

      Since I last posted here, while I've been working on other cars ... I've been studying wiring diagrams at home ... LOTS of them!

      The engine harness was simple ... I used the 2008 Jetta harness that came with the engine. For the chassis harness connections, I used Bentley wiring diagrams and Excel and mapped out all of the pin-outs and wires colors for both my existing 2007 Passat 2.0t chassis harness ... and the 2008 Jetta 2.5 chassis harness plug that I was going to graft on. I matched up all the functions, and what wires need to be spliced with what wires. Then I actually checked the Passat chassis plug and the Jetta chassis plug to verify that the wire colors and pin numbers were correct (I've discovered that wiring digrams are not always correct!). Doing one wire at a time, I've got the Jetta plug spliced onto the Passat harness. I finished that up last week.

      I've discovered that there are quite a few wiring differences between the 2.0t and 2.5 cars. For example, the 2007 Passat 2.0t uses no relays to energize the fuel pump, (it uses what's called a Fuel Pump Control Module) nor does it have a return-to-tank fuel system! The result is, I get 90 PSI fuel pressure at the engine! I had to take a trip to the local Pull-a-Part and purchase a fuel pump with both pressure and return lines, a 4.0 Bar (58 PSI) fuel pressure regulator, the J17 and J643 under-dash relay system for the fuel pump ... and ... oh yes ... a 2.5 trunk emblem from a 2004 Nissan Maxima (they're BIGGER than the VW ones!). I trashed the 2.0t emblem.

      I've yet to install the Jetta fuel pump and pressure regulator though ... I'm still running 90 PSI.

      The other odd thing is ... the dual fuel pump relays cause the fuel pump to run ... when you open the driver's door! (to prime the system I presume).

      Got everything wired up the end of last week ... and tried to start it ... NOTHING! After some extensive checking, I found that I had no check-engine light during starting ... a sure sign of ECU issues (yes, the one I paid $60 to have the immobilizer disabled - although I don't think it's anything he did - it may be something I did). After going over all of the wiring extensively (again) I purchased another ECU from the same Pull-a-Part Jetta and installed it. I now had a check-engine light!

      THE CAR STARTS UP! (but obviously quickly dies because of the immobilizer).

      I may just take the car to the local VW dealer and have them program the ECU Immobilizer ... but first I've got to modify the existing fuel system with the Jetta regulator and fuel pump ... I should only have 58 PSI at the engine. The Passat also uses two ECU relays for some reason, J271 and J670 ... probably because the turbo engine had so many other electrical parts ... electric coolant pump, HPFP, wastegate bypass valve, etc. I've got to verify that I actually need the J670 relay, and what it actually drives.

      Once I've double and triple checked everything (I'm still not sure the fuel pump is wired properly) ... I'll reinstall the ECU and take it to the dealer.

      After this project, I can see I'm going to have to get some computer software to read this new computerized stuff now-a-days.

      My goal with this project is to have EVERYTHING work in the car just like from the factory ... with NO check-engine lights. This is obviously turning into a LOT more than I was expecting!

      I REALLY am hoping to get this car where I can actually DRIVE it before the end of the month (of course I said that a month ago too)!

      I'll keep you all posted!

    5. Member jddaigle's Avatar
      Join Date
      May 30th, 2003
      Denver, CO
      2008 Passat Wagon VR6 4motion, 2013 FIAT 500 Sport
      03-21-2017 09:39 AM #30
      I admire the commitment! Sounds like your on the home stretch.
      - Jeff
      B6 Passat 3.6 & 4motion Resource Thread
      Now: 2008 VW Passat 3.6 4motion Wagon, 2013 Fiat 500 Sport
      Then: 1987 Volvo 745GLE, 1989 Volvo 740GL, 1994 Volvo 940T, 1995 Infiniti G20, 2000 VW Passat 1.8T, 2001 VW Jetta Wolfsburg Ed (x2), 2004 VW Golf TDI, 2006 Jetta TDI

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