Unable to connect to ECU

[andante1]

hello everyone.

i have a MK3 golf with a 1.9 TDI swap ( AHU ) and i am unable to connect to the ECU using an OBD scanner.

i have tried 3 different scanners and 2 of them were from a shop and they cant even detect the protocol.

i have searched and searched but cant really find whats missing.

here is what i know:

1. the OBD port has power
2. according to the wiring diagrams i found on the service repair manual, the k-line wire that goes to pin 7 on the OBD connector is grey/ white
3. underneath the steering wheel i can see a white plug like the one on the right with the same yellow and grey/white wires and they are not connected to anything
4. i have this bridge and the grey connection port only has two wires, one grey/white and another one blue/grey, i dont know where the grey/white leads to
5. i cant find this "board" anywhere, my grey/white with the red connector is not connected to anything at all and the grey/white with the brown connector is connected to a grey wire with a brown connector as well

i am unable to test / measure circuits at the moment because i lack a multimeter.

am i missing that board i mention in the fifth point and thats whats making me have issues with the connections? or is that something specific to another model and i just have something messed up?

any kind of input is appreciated.

thank you!

 

[volksguy]

Depending on the wireing and ECU sounds likes its ODOD were you need a Ross Tech Vagcom for it to read as its Not OBO2

 

[volksguy]

Depending on the wireing and ECU sounds likes its ODOD were you need a Ross Tech Vagcom for it to read as its Not OBO2

 

[Abacus]

I am unfamiliar with what you had for cars in Portugal or how they were configured from the factory, but in the US the early 1996 TDI cars had a black plastic computer (ECU) that had the OBD-D programming from VW. It could only be read with a VW program, or the Ross-Tech VCDS (Vag-Com), nothing else would read it. VW issued a recall and swapped those computers (among other things) with the silver case ECU that was OBD-II compliant and could be read with a standard code reader.

 

[andante1]

hello @volksguy and @Abacus, thank you for your responses. changing the reader type wont change anything because i was able to do a continuity test on pin 7 of the OBD connector and i can see that the pin in not connected to anything - i mean, it has to connect to something, right? the OBD port only has 4 wires, power, ground and two data links ( l-line and k-line i think ) and according to some website / forums the one required for reading error codes is the k-line one. also, its a 1997 model

 

[volksguy]

SIR What ECU Do you have 028906021GQ ? Or 028906021BA Or 028906021FA

 

[Abacus]

It’ll be written on the top of the ECU.

 

[andante1]

SIR What ECU Do you have 028906021GQ ? Or 028906021BA Or 028906021FA

im sorry, my ECU casing has nothing written on it, i can tell you its a plastic casing and not the aluminum one. is there any other way i can identify it?

 

[volksguy]

Hello Then most Likey its the O28906021BA. A OBOD System Need a RossTeck Vagcom download and RossTeck Cable to Talk to it.
The RossTeck will work on all Late Model VW Allso.

 

[andante1]

Hello Then most Likey its the O28906021BA. A OBOD System Need a RossTeck Vagcom download and RossTeck Cable to Talk to it.
The RossTeck will work on all Late Model VW Allso.

hey, sorry for the delay. how is the connection setup? where do the wires go then?

 

[Abacus]

The cable is like a regular OBD-II cable, so it just plugs into the port. It's found on the Ross-Tech website for new, but stay away from fake cables out there since they do not work.

 

[andante1]

The cable is like a regular OBD-II cable, so it just plugs into the port. It's found on the Ross-Tech website for new, but stay away from fake cables out there since they do not work.

nono, not the connection vagcom -> obd. my question was for the connection obd -> ecu