OBD2 not connecting

2004 AUDI A4

170,000 MILES • 1.9L • 6 CYL • TURBO • 2WD • MANUAL

DAVE321123

MEMBER
1 POST

My check engine light is on but bag com cannot find the ECU? Anyone have any ideas? The OBD socket is clean and I have checked all the internal fuses.

Nov 26, 2018 at 4:55 AM

JACOBANDNICKOLAS

✓Experienced Mechanic
110,246 POSTS

Hi and thanks for using 2CarPros.

If you confirmed power and ground to the DLC, then there has to either be an issue with the ECM or the wiring to it. From the DLC (pin 7 ) there is a green/red wire that runs to the comfort control module, ECM, and TCM. I have attached a schematic for you to see. Chances are there is a problem with one of the splices.

By the way, I had to break the schematic in two because of size.

See if this helps and let me know.

Joe

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