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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH996 Immobilizer Circuit
Leading reported evidence
Replace 2004 gt3 into my 2000, i used everyting
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
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Performed · outcome unconfirmed · Original poster
i will add that when i swapped the 2004 gt3 into my 2000, i used everyting from the 2004, dme, immobilized and key fob.
Leading evidence: 'Replace 2004 gt3 into my 2000, i used everyting' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Clean immo back new status' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Discussions that performed work without a confirmed outcome
1
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Performed · outcome unconfirmed · Original poster
I have a 99 996 Cab (149k) for which I recently replaced the motor with an 03 3.6L engine (33k).
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Performed · outcome unconfirmed · Original poster
I've been told an aftermarket security system cannot be done due to the type of structure/mechanism for the door interfaces used by Porsche.
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Performed · outcome unconfirmed
Diagnostic mode is used by tuners like Cobb to reflash the ECU maps, which are in the main flash not the EEPROM.
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Suggestion · Original poster
As part of my quest in gathering knowledge on this "System", I did call "Specialized ECU Repair" in FL and I am going to give them a shot at fixing my issues with the ECU/DME vs Immobilizer.
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13 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261026T144035Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
I have a 99 996 Cab (149k) for which I recently replaced the motor with an 03 3.6L engine (33k). Swapped out the whole Harness, the Switch "Assy" (including 'new to me' Key w/ missing logic board), ECU/DME, and Gauge Assy. I don't believe the Immobilizer Unit, under the Driver's Seat, was touched. Vehicle runs and is impressive over the original 3.4L engine.
I need some help with the Immobilizer Circuitry. So here's what I have remaining; 1999 Door Lock Controllers in both RH & LH doors (w/ 1999 Key/FOB) and the 1999 Immobilizer/Controller (under Dr seat). So my issue is that I can't program a new key, or set/reset the Immobilizer Circuit at all (w/ either Key). The P-Dealer took a look at it and couldn't get it done. I provided the VINs that each component came from. There were 4 different VINs involved from the original one (1999) & the 3 from the donor cars (2001 & 2003 twice). But the dealer said none of them worked. They wanted to sell me a new ECU/DME for a "BUNCH" of cash.
I already figured if I have to replace the ECU/DME (again), I'll definitely go for another, low mileage, used part. But I have an electronics tech & Engineer background, so I would just like to understand the circuit before I give up on a "fix" and go with the part swaps. Is there a "step-by-step" circuit description to go with the appropriate circuit diagram(s)? If so, where can I get them?
TIA
Jamie
What u r asking for doesnt really exist. Ecu doctors can marry the componemts because its a high encryption software thing. They have figured out how to do it by probaby sending a $hit ton of money or they had an inside guy devolop their software. There is no way they r putting that info out there, good luck.
i will add that when i swapped the 2004 gt3 into my 2000, i used everyting from the 2004, dme, immobilized and key fob. I just swapped the old key blade into the fob. The rfi pill in the fob, immobilzer and dme are all married so it all works 100% in my car.
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i will add that when i swapped the 2004 gt3 into my 2000, i used everyting from the 2004, dme, immobilized and key fob. I just swapped the old key blade into the fob. The rfi pill in the fob, immobilzer and dme are all married so it all works 100% in my car.[/QUOTE]
That may turn out to be my biggest mistake. I didn't replace the Immobilizer AND I didn't ensure that everything came from the same car (VIN). Now I just need to find the least expensive (LOL), way to fix it. I've been told an aftermarket security system cannot be done due to the type of structure/mechanism for the door interfaces used by Porsche. So I'm kind'a stuck getting the Porsche systems to work.
Ideas?
TIA
Jamie
Yes, your immobilizer is your problem. Once an Immobilized is programmed to a DME, it is "married to that DME" and cannot accept any other DME. So your Immo is still married to the '99 DME.
I actually don't see how it's even running !! ( you did some by-passing right?)
Anyway the Porsche dealerships cannot divorce the Immo, they can only program new Immo's . I had heard that ECU Doctors could clean an Immo back new status, but I have no first hand knowledge of them actually doing it, or the cost..
Unfortunately the only 2 options i see r ecudoctors or get the key, immobilizer and dme from the same car. DC Auto in nc is real good dismantler. Maybe they will trade u?
Btw the guys at ecudoctors r very easy to work with just give them a call
So nobody has the actual Circuit Description? I know I can pickup the Circuit Diagrams and trace the circuit(s). But I'd love to have the narrative of the expected connections, flow & timing of the circuit(s).
Com'mon guys, there are some people on here who really understand these Systems. Is there really no one who has used this type of tool to figure out an electrical issue at some point? Or you're telling me no one on here understands the Porsche methodology?
Sorry if this seems a bit aggressive, I'm just really a frustrated ex-computer repair person. I'd really like to understand the circuit and fix it myself. I'm hoping that the people with the appropriate knowledge just haven't seen the post yet.
There is no circuit. The immobilizer, ECU, and cluster communicate on canbus. Each has the VIN# programmed. If two of the three VIN#'s match, AND the pill in the key matches the immobilizer, the immobilizer tells the ECU that it's OK to run.
The Mk2 is what I am more familiar with. The Motronic 7.8 ECU has a 2kb EEPROM that holds the vehicle-specific configuration including the VIN#. There is a software tool that can boot the ECU in diagnostic mode and read out or reprogram the EEPROM. Diagnostic mode is used by tuners like Cobb to reflash the ECU maps, which are in the main flash not the EEPROM.
In theory, you can read out the EEPROM,change the VIN#, and reload the EEPROM. The VIN# is in plain-text. However there is an ecrypted version of the VIN# in the eeprom somewhere. If things don't match the ECU throws codes.
The ME 7.2 ECU is a lot simpler. In that ECU there is still a 2kb EEPROM, and the VIN# is still encoded in the EEPROM. In this ECU there is a way to permanently disable the immobilizer and it's as simple as changing two bytes in the EEPROM. Search "VW Immobilizer Defeat" on ebay and you'll find many places offering the service for as little as $50.
The Mk2 cluster also contains a 2KB EEPROM, it's a 93c86 microwire EEPROM set for 1kx16 bit organization. It also has the VIN# stored in plain text, and supposedly encrypted in there somewhere as well. Same story, you can read out the EEPROM and change the VIN#, you also need to change the encrypted VIN# somehow. If the cluster is unused PIWIS can set the VIN# and mileage to match whatever you want. Once the cluster has been programmed PIWIS cannot reset the VIN#. Supposedly there is a way to reinitialize the cluster, at least the VW & Audi clusters that use the same internal software can be "virginized" as they call it.
If you really want to geek out, read up on the Megamos Encrypto Transponder( RIFD)
The RFID sends out a signal that is picked up by the antenna ring around the ignition switch, the antenna relays the signal to the receiver mounted on the steering column, the receiver then sends a modified signal to the Immobilizer, The Immobilizer decodes the Encrypted signal and if OK sends a signal to the DME, if the DME recognizes the code as correct, it sends a signal back to the Immobilizer, once the Immobilizer receives the signal back from the DME that it also approves, the Immobilizer sends a signal back to the DME that it's OK to allow the car to start .........
PS : this is as "geeky" as I get, no need to ask me anything that is "deeper geek"..lol
Thank you for each of the responses. As part of my quest in gathering knowledge on this "System", I did call "Specialized ECU Repair" in FL and I am going to give them a shot at fixing my issues with the ECU/DME vs Immobilizer. I gave Jorge a call and when we were through chatting, I decided to use their service. When I get it all sorted, I'll give ya'll an update.
Thanks again. And no, I'm not giving up on getting to know the intimacies of the Porsche electronics. LOL
Jamie
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