This subject comes up very often. There are posts that explain how to do it, but they are deep inside other threads. So allow me to gather all the info in 1 thread:
I'd like to have a howto guide thread to point to when our new members ask how to connect to their special ECUs. The Airbag and ABS
ECUs, particularity. This guide adds switches to the existing cable; another option is to buy adaptors to insert in the male port of the interface. I think we should re-learn the handy skills that make us humans
, and start doing stuff ourselves.
I bought 8 of these KL + OBD2 USB cables. Do a ebay search and find the cheapest ones + shipping. I paid ~6£ each.
This guide is for the vast majority of Alfas, except Mito and Fiat500, which use ELM. The software used is FiatECUScan, for it's wide compatibility, but does not exclude any other software. The modification of the cable is not software-specific.
If I can do it, anyone can!
In the interest of saving money and time, please check out this howto guide.
1) Look up your car model and ECU you want to connect to. FiatECUScan - Fiat, Alfa, Lancia ECU Reader / Scanner
You will identify what modification you need to apply to your cable. The modifications performed in this guide is OBDKey1 (ABS) and OBDKey3 (Airbag). But you may OBDKey9 (for some GTV power steering ECU), and OBDKey12 (for Xenon).
2) Open up your interface. (See image #1) Check out how the K-Line pin, pin#7 is connected to the chipset and if it is possible to insert a switch between this connection. (Image #2) The purpose of this modification is to be able to move the signal of pin#7 to another pin
: 1,3,9 or 12, respectively, or back to the original pin#7. Simple!
--On my OBD chipset, I found the K-line came from the 3rd pin on the chipset and went to the male connector. I found the resistance is 0 between that pin on the chipset. Warning: There are 2 other pins that also link to the K-Line, with resistance from the chipset; ignore those.
3) After understanding the concept of steps 1 and 2, now find the solution. For me, I soldered a switch that allows me to assign the K-Line signal to pins 1(ABS),3(Airbag),7(Motor/Gearbox). Why use a switch at all? Why not just join all 3 together? I heard that shorting 7 with other pins can be dangerous. It should be ok for most cars to just short all 3 together but I prefer to be safe, especially when airbags are involved (Experienced members, your input would be appreciated here).
So, I snap off the connector going to Pin #7. Ideally, find a switch that allows to redirect to 1,3,7,9 and 12. All I could find here was a big 6-pin switch (Image #3) at scrap yards.
A) Are you crazy? Don't do it.
B) You may instead use wires wind up around the connectors, and held in place with hot glue. This can be removed easily too.
C) Soldering on factory chipset is a pain. If you really want to do it, scrape off, cut off the factory soldering to reveal clear metal underneath - so the solder will hold. Took me a couple of hours and neck pain to get all points done.
D) Just don't. Don't do it.
4) I cut a tiny hole in the plastic and used hot glue to hold the switch in place. Also used hot glue in the inside to make sure the cables and solder is strong. I'd hate to have to go back inside and do the soldering again... (Image #4)
5) Test the performance of your circuit with your multimeter. There should be 0 resistance when the switch is activated to a certain pin, and infinite resistance on the 3 other pins. Test with FiatEcuScan on your car, using the Scan Function to identify modules. If you try to connect and get a ISO error, you selected the wrong version of your ABS or Airbag. The scan function helps you select the correct one.
Credit: this thread: http://www.alfaowner.com/Forum/alfa-...ml#post3550068
, FiatECUScan site, Klaudiusz and many, many others... Thanks!