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Discussion Starter · #1 · (Edited)
The Rabbit TDI Project
Part 6: Wiring 3: Of Keys and Readers, IMMO3

Or: Throbbing headaches of antitheft

My TDI engine has an Immobilizer.
IMMO3 = good idea, but not for retrofitting engines to older cars.

The IMMO system consists of three parts, the ECU, the cluster, and the key/key reader. The ECU must know the cluster, the cluster must know the ECU and the keys. The keys, well they're just hanging around because they have nowhere to go.

My cluster was brand spanking new, my ECU was used, my key came from Ebay.

With the TDI engine and cluster, my 1982 Rabbit is now OBDII, complete with communication port. A borrowed laptop and a VAGcom license lets me communicate with my cluster and ECU.

Coding the ECU to the cluster was a pain. There are vast threads on the TDI club forums about this, so I won't go into it here. But one of the main things is that there must be no DTCs (Diagnostic Trouble Codes) and you must get the SKC (Secret Key Code) from the dealer.

I don't have ABS, and I don't have Airbags, so I'm guaranteed to have two DTCs in the engine computer. Plus, the local dealer refused to tell me my SKCs. Grrrr....

The solution: Christmas.

I took holidays over Christmas, and travelled back to Manitoba, the land of my people.
I took my key, ECU and cluster home for the holidays. Using my parents TDI as the donor car, I sweet talked my way into the back shop at a Winnipeg dealer. I did the wrenching, and they sent a tech over to do the coding.

Actually, they sent a tech-trainee over who had never done it before, but that's a different story.

Anywho, a piece at a time, coded my ECU to the other car, coded my cluster to my ECU, repinned the cluster connector to use my key reader, and coded my key to my ecu and cluster. Oooohhhh, magic.

Ok, so what next?
I did some investigation into keys and lock cylinders and such:

The Cabrio lock cylinder fits into the steering lock of my 1982 Rabbit. Cool.

Dave get's to use a switchblade key.

But I had to get a switchblade key cut to fit, as they aren't native to the Cabrio.
There are different kinds of IMMO keys. There are various types of fixed code and change code.

If you buy a G/JIV lock cylinder, it comes with "W" keys, and a permanently attached key reader, but it doesn't fit into the steering lock of the older cars. The switchblade key is a "W" key.

The Cabrio lock cylinder comes with "W3" keys, and you have to buy the key reader seperately.


The IMMO in the G/J cluster, connected to the Cabrio reader, doesn't recognize the W3 keys. It does recognize the W keys.

For my current setup, I'm using a cabrio reader, and a used W switchblade
key, buried up under the dash, with a 2002 cabrio lock cylinder for the
steering lock.

I don't know why the W3 keys don't work.
The W3 keys work with the cabrio reader with the cabrio IMMO box.
The W3 keys work with the G/J reader with the G/J IMMO,
but not with the cabrio reader and the G/J IMMO.

summary: IMMO3 is a pain

Stay tuned...


Part 1: Introduction
Part 2: Installing the Engine
Part 3: Transmission
Part 4: Wiring 1
Part 5: Speedometer and Cluster
Part 6: ImmobilizerIII
Part 7: Drive By Wire
Part 8: Intercooler
Part 9: Intake and Exhaust
part 10: MFA and Cruise Control
Part 11: The Dash
Part 12: The Little Things
Part 13: The End (for now)
Part 14: 6spd transmission and brake upgrades
One Year Later
Dyno results
Who Needs a VR6
TDI Rabbit

1,923 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (MrDave)

Man, I just love following this project. Very cool.

327 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (MrDave)

This is so interesting! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif

758 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (Frenchguy)

sweet ride. im planning on puttin a TDI in a westy. this will be a nice thread for me to learn from your mistakes.
cheers mate

62 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (jwspin)

Hey Dave!
I said it before, and I'll say it again ,GREAT JOB! http://****************.com/smile/emthup.gif !! The info you are giving here is priceless, and will help me greatly when I start my TDI mk.2 Jetta project next month. Keep it up!

Modified by 1.8t80rabbit at 4:59 AM 5-6-2003

406 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (1.8t80rabbit)

Quote, originally posted by 1.8t80rabbit »
Hey Dave!
The info you are giving here is priceless,

My sentiments exactly!! I have a 2001 1.8t sitting in the garage awaiting it's new home in my 96' golf. I have the ECU and engine harness, but that's where practicality ends, and the "fun" begins. This post is a huge breath of fresh air, thanks http://****************.com/smile/emthup.gif

1,509 Posts
Re: The Rabbit TDI Project: Part 6: ImmobilizerIII (i81b4u)

Yeah!! I'm learning tooo. I'm planning on putting a 2.5 TDI into a newly acquired underpowered Rialta. I fugured the 2.5 TDI should be as torque monsterish as the new 32v VR6 and only slightly less HP. Whould make for a fun camper
Course, this won't start till next winter, after camping season
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