OBD2 not connecting

Tiny
DAVE321123
  • MEMBER
  • 2004 AUDI A4
  • 1.9L
  • 6 CYL
  • TURBO
  • 2WD
  • MANUAL
  • 170,000 MILES
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.
Monday, November 26th, 2018 AT 12:55 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,328 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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Monday, November 26th, 2018 AT 5:53 PM

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