02 TDI ALH ECU/ECM Swap?

jksuperstar

Member
Joined
Aug 7, 2007
Location
Denver
TDI
2002 (ALH)
Backstory: My 02 Golf (ALH) had some declining performance, and an odd power issue where I turned off the car once, and suddenly all power to the car was lost (I realized this walking away, when the remote didn't lock the car, so I jumped back in and instr cluster was reset, no power to anything, etc). So I stuck the key back in, turned to ON, and instantly everything powered back up. Damn strange. Two days later, the car wouldn't start...it turned over strong, but never fired up. I connect VCDS, and could see the auto-trans TCM, and the cluster, but I had "Too Many Communication Errors" with the ECM. I connected an Alientech Powergate and it couldn't find an ECM either. Before this, for a week, while driving I'd get 3 beeps, but no lights, no blinking, no CEL triggered, and no codes to be retrieved. That happened about three times.

I'm guessing the ECM is shot. I ordered a used one off ebay. I've got some info about what to do when it arrives from the ross-tech site. But I'm still confused about exactly what info I need to get the new ECM up & running, and keys working.

I have an old VCDS log from the original ECM, so I have the Immo-ID, VIN, etc. Do I still need a PIN for the keys? Or since the keys & Immo are the same, will that not matter?

Also, the way the ECM died was strange. Any how-tos or helpful hints about checking power to the ECM? Or anything else? I've tried searching this and other forums, but ECM, ECU, and details about the Immo are mixed and sparse. I'll gladly take some links to existing info rather than start a new thread if the question has been answered thoroughly.

All help appreciated!!
 

jksuperstar

Member
Joined
Aug 7, 2007
Location
Denver
TDI
2002 (ALH)
One more thing, I pulled the ECM, and tried to start the car for kicks, and it acted the exact same way...turning strong but not firing up (duh!). But that was just a sanity check that the ECM was the culprit.

With the "dead" ECM in, I don't see glow-plug lights, but still see the other cluster lights after entering "ON" position of the key.
 

jksuperstar

Member
Joined
Aug 7, 2007
Location
Denver
TDI
2002 (ALH)
Got a used ECM on ebay, towed to a stealership, and had them reprogram the ECM. Got screwed. Took them two and a half hours to do as well. At least the car is running again.

Apparently there's no way for VCDS to do this. At least, not that Ross-tech will support. Aside from knowing the Immobilizer ID (which can easily be found by VCDS), you also need the SKC code for BOTH old and new ECMs. Possible to get the old ECM SKC from the Immobilizer or Instr Cluster, but you have to read the whole flash/eeprom in order to do it, and even then you need vag-commander or such tool, which is $$$$. Also, getting the SKC codes from VW is impossible since 2005, as their VAG tools talk directly to the factory servers, get the SKCs for the units, and program directly, no human eyes can see these for security.

That can all be boiled down to this: If you're lucky to find a locksmith with all the appropriate tools and certifications from VW, they can do it, but most likely you have to go to the stealership to get your used ECM programmed to work in your car with your keys.

SKC = (Secret Key Codes)...or PIN# that is a 4-7 digit code to unlock access to changing the immobilizer ID or VIN# in a used ECM.
 

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Hi, I hope you checked all the related fuses, grounds and plug connections before going to this step.
I had a similar power loss/ cluster reset after turning my car off which triggered the car alarm while I was still behind the wheel... it has never recurred since. Obviously not the ECM but maybe something with the IGN switch in my case. :confused:
 

jetta 97

Vendor
Joined
Dec 25, 2008
Location
Dallas (McKinney) ,TX ,USA
TDI
2 X Jatta MK5 2006
Got a used ECM on ebay, towed to a stealership, and had them reprogram the ECM. Got screwed. Took them two and a half hours to do as well. At least the car is running again.

Apparently there's no way for VCDS to do this. At least, not that Ross-tech will support. Aside from knowing the Immobilizer ID (which can easily be found by VCDS), you also need the SKC code for BOTH old and new ECMs. Possible to get the old ECM SKC from the Immobilizer or Instr Cluster, but you have to read the whole flash/eeprom in order to do it, and even then you need vag-commander or such tool, which is $$$$. Also, getting the SKC codes from VW is impossible since 2005, as their VAG tools talk directly to the factory servers, get the SKCs for the units, and program directly, no human eyes can see these for security.

That can all be boiled down to this: If you're lucky to find a locksmith with all the appropriate tools and certifications from VW, they can do it, but most likely you have to go to the stealership to get your used ECM programmed to work in your car with your keys.

SKC = (Secret Key Codes)...or PIN# that is a 4-7 digit code to unlock access to changing the immobilizer ID or VIN# in a used ECM.
You can do it with VCDS , but you will need some extra tool to read Eeprom of ECU or cluster.

I can do it, I wish I have see this before , I could help you.
 

jksuperstar

Member
Joined
Aug 7, 2007
Location
Denver
TDI
2002 (ALH)
I have swapped in the old ECU a couple times since the new one is working (as not only a sanity check, but if my old one still worked I'd sell it for $). Nada...new ECU works fine, old one is completely not reachable by the two tools I have (VCDs and Alientech Powergate).

I know vag-commander or such can read the EEPROM, and the PIN extracted. But I also needed the car back up & running asap.

Just before the ECU died, I was having some low power / limp home issues intermittently. They've developed into something more permanent. So I'm on to replacing the vacuum lines and checking the N75/VNT Actuator ...
 

Rein

Member
Joined
Mar 11, 2023
Location
Hawaii
TDI
Alh
You can do it with VCDS , but you will need some extra tool to read Eeprom of ECU or cluster.

I can do it, I wish I have see this before , I could help you.
What all do I need in doing the ecu swap?
2003 vw golf 1.9tdi got the ecu to swap how do I program the ECU?
 

Nuje

Top Post Dawg
Joined
Feb 11, 2005
Location
Island near Vancouver
TDI
2015 Sportwagen; Golf GLS 2002 (swap from 2L gas); 2016 A3 e-tron
Seems to be the day for 10+ yr-old thread resurrection. :)

Here's the how-to on swapping ECUs.
You need VCDS from Ross-tech; and a way to get the SKC. Look for "free VDS alternative" thread on this website for a way to do that with cheap hardware and free software.
 

jetta 97

Vendor
Joined
Dec 25, 2008
Location
Dallas (McKinney) ,TX ,USA
TDI
2 X Jatta MK5 2006
What all do I need in doing the ecu swap?
2003 vw golf 1.9tdi got the ecu to swap how do I program the ECU?
Easiest way is if you sent me ECU , I can simply do Immobilizer delete and ECU will be plug and play.
For more Info send me message or email me ( email in my signature)
 
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