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OBD-II port dead, Check engine light on, Truck runs fine.

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by ecomike, Jul 7, 2012.

  1. ecomike

    ecomike New Member

    It is a 2004 Chevrolet Silverado Z71 5.3L V8 4WD. I need to know which fuses (fuse ID number and location) being blown might allow the truck to run, but that would kill the OBD-II data port signals?

    Recent dealer inspection says it needs a new O2 sensor, but we can not get an OBD-II signal at the port. I suspect a fuse, or fuses are blown (had the same problem recently with the Saturn, and it was a blown PCM-B fuse in the PDC under the hood, 2001). Need some help. I am new to this beast.:glasses: But not new to diagnostics....
  2. ecomike

    ecomike New Member

    Forgot to mention, the check engine light is on, and everything else seems to work!
  3. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

  4. ecomike

    ecomike New Member

    Well, I don't have the truck here, but just got a call that the cigarette lighter fuse, 15 amp is bad. I won't know till tomorrow if it fixed the OBD-II, or if there are more fuses in the path to find? I am wondering if the O2 sensor issue is related. I told him to check the sensor and wiring for any off road carnage.
  5. Sierraowner5.3

    Sierraowner5.3 Rockstar 3 Years 1000 Posts

    i had a dead OBD-II in my 05 sierra. was the 15 amp cigarette lighter fuze that caused the issue. should be no other fuzes to worry about. kinda one of the weird things GM did.

    swapped fuzes out with a good fuze and away i went.

    Alex
  6. RayVoy

    RayVoy Active Member 2 Years 1000 Posts

    That's it Mike, someone just overloaded the power outlet.

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