ALH ECU IN MK3 with AHU TDI

Freakoboost1

Active member
Joined
Jun 10, 2022
Location
Lynden
TDI
98 AHU JETTA
Getting a very well built AHU long block soon and wanting to go to an ALH ECU for flash tuning. How difficult is it to swap ecu’s from an ALH into my mk3 Jetta?
 

garciapiano

Veteran Member
Joined
Feb 12, 2018
Location
Southern California
TDI
1997 Jetta TDI (1Z)
You don’t need the ALH ECU to run the ALH… you can absolutely use the stock wiring for the AHU. But yes, flashing is way more convenient than swapping chips.

There are tuners in Europe I’ve talked to on fb that that sell a “plug and play” harness to adapt the ALH ECU but I’m leery of that. That sounds way too easy.
 
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JordanTr

Veteran Member
Joined
Mar 28, 2022
Location
Kimberley, BC
TDI
1996 B4V x3, 2006 Dmax, 2005 Allroad, 2005 BHW
There’s a YouTube video of a guy cutting/splicing to run ALH management on AHU as well. It was for a swap so he didn’t really touch the mk3/b4 chassis integration.
 

jimbote

Certified Volkswagen Nut
Joined
Jul 10, 2006
Location
spiral arm, milky way (aka central NC)
TDI
Tacoma 4x4 converted to TDI
Might be an easier task to start with a standalone mk4 harness and feed the mk3 cluster just what it needs to function. On my AHU van every bit of the engine management hardware is mk4 including injection pump, crank sensor, temp sensor, R109, glow relay etc. I even built a loom bracket to hold the mk4 ip, crank, and needle lift connectors using the stock mk4 piece. Bolts between the block and coolant outlet flange. You can even repin the stock AHU pump into an mk4 connector.
 
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