OBD2 port not communicating?

WFFWFF58

MEMBER
2000 AUDI TT
1.8L
4 CYL
TURBO
2WD
MANUAL
28,000 MILES

Radio has no power. Obd2 port not communicating. Tried several different code readers including my mechanic's reader. Tachometer and speedometer not working. Heat gauge and fuel gauge fluctuate from lowest to highest reading available on the gauge, every second.

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

There are two fuses (#7 and #12) that run the ALDL diagnostic connector we need to check. Here is a guide to help and the fuse locations in the images below:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Here are the ALDL connector wiring diagrams well. The fuses are in the left side of dash fuse panel.

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Sunday, November 26th, 2023 AT 2:21 PM

WFFWFF58

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4 POSTS

Yeah, I was hoping that was the issue. I checked fuses 7, 12, and 42. All are good.

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Sunday, November 26th, 2023 AT 4:46 PM

WFFWFF58

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4 POSTS

Thank you so very much for reaching out!

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Sunday, November 26th, 2023 AT 4:49 PM

KEN L

MASTER CERTIFIED MECHANIC
47,513 POSTS

Okay, I would test the scanner on another car to make sure it works and if so, let's use this guide to help test the ground wire of the ALDL diagnostic connector (brown wires):

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Connect the test light to power and let me know.

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Monday, November 27th, 2023 AT 9:09 AM

WFFWFF58

MEMBER
4 POSTS

Hi Ken!
Traveling today for business. I will test the ground wires, pins 4 and 5 Tomorrow and then let you know what I find. Thanks again for your help!

William