ODB-II Port fuse location needed

Tiny
JOHNBIER
  • MEMBER
  • 2005 HONDA CIVIC
  • 2WD
  • AUTOMATIC
  • 165,000 MILES
How do I find which fuse controls the power to my ODB-II Port?
Monday, June 6th, 2022 AT 6:35 PM

5 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,265 POSTS
There isn't an individual fuse for the OBD port on that car. However, if you are trying to figure out why the port doesn't have power on pin 16 like the standard calls for it is because Honda didn't power pin 16. It's one of the issues with Hondas and some scan tools. They put power on pin 8 instead. Attached is the schematic for the data lines on that car.
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Monday, June 6th, 2022 AT 11:29 PM
Tiny
JOHNBIER
  • MEMBER
  • 3 POSTS
Okay, I guess. However, now what? I am not trying to figure out anything as to the power to pin 16, pin 8 or any of the other pins specifically, and if I am, I do not understand why. All I know is that I had 2 mechanics tell me that their diagnostic machines cannot read any codes. The first guy told me he didn't know why. The second guy told me that I should look for a blown fuse. I watched a 10-minute video that 2CarPros produced and at the end, it said to submit a question to find out which fuse controlled what the video called an ODB-II port. I was confused by the term ODB-II as opposed to OBD (on board diagnostic?). In any case, I am not sure where to go from here. No one seems to know what to try and fix without being able to read the error codes associated with my car. Any help would be appreciated.
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Tuesday, June 7th, 2022 AT 5:29 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,265 POSTS
The early system up until 1995 was the ODB system, it used a different style port than the newer OBDII port that came out in 1996 and up like your vehicle has. A common reason for a scan tool to not read is a lack of power or ground on the OBDII port. The problem with Honda is that they didn't make the port to the full standard, so some scan tools won't work on them.
To use a scan tool with them you use an external power source like a power adapter to power the scan tool, so it doesn't look for power from the car. The other option is to add the correct pins into the connector to provide the power and ground connections in the port.
I've done that a few times for damaged or like your vehicle where the pins are missing.
There is no fuse to replace to get the power there as the actual pin is missing. Repairing it would take adding those pins or making an adapter harness that includes the missing pins.
Attached is the common pinout for the OBD II port. If you compare it to the wiring yours shows you can see the differences. Yours is missing the ground at pin 5 and the power at pin 16. It's likely that if you added those pins into your connector that the scan tools they are using would work.
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Tuesday, June 7th, 2022 AT 7:05 AM
Tiny
JOHNBIER
  • MEMBER
  • 3 POSTS
Thanks, that's helpful information. I am guessing that since I used two different code readers on this car previously without there being an issue, something has happened between then and now to make it so that is no longer possible. In something I saw last night, it suggested that the connection of the code reader to the port was not a good connection and that this could also be a cause for the code reader not being able to register a code. It suggested either tightening the holes where the pins connect or replacing that piece. I guess that is the route I'll take next.
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Tuesday, June 7th, 2022 AT 7:20 AM
Tiny
STEVE W.
  • MECHANIC
  • 13,265 POSTS
Some code readers will use the power from pin 8, but that isn't that common for the higher end tools.
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Tuesday, June 7th, 2022 AT 10:53 AM

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