There is not one. The is an ECU fuse.
The fuse for the diagnostic terminal on a 2004 Cadillac Escalade is typically located in the vehicle's fuse box. The primary fuse box is found under the dashboard on the driver's side, while a secondary fuse box may be located in the engine compartment. To identify the specific fuse for the diagnostic terminal, refer to the fuse box cover or the owner's manual for a diagram that indicates the exact fuse number and its function. Always ensure the vehicle is off before checking or replacing fuses.
The lower right hand fuse closest to the transmission tunnel is the fuse, if there is 1 in there already! then you are probly getting codes flashing all the time with engine running or not. IF code 12 ONLY with engine OFF just remove the fuse.
The owners manual shows ( fuse # 110 - 20 amp cartridge fuse - for diagnostic connector power and cigar lighter )
The OBD2 diagnostic port doesn't have a fuse and isn't powered by its own circuit.
On a 2004 Toyota Avalon, terminal TC (Test Connector) is typically used for diagnostic purposes, allowing access to the vehicle's onboard diagnostic system. Terminal E1 is the ground terminal for the diagnostic connector. Together, these terminals help facilitate communication with diagnostic tools when troubleshooting the vehicle's systems. For specific pinout information, it's always best to consult the vehicle's service manual.
For a 2004 Saturn, the fuse responsible for the diagnostic port is typically located in the under-hood fuse box. You should check the owner's manual for the specific fuse number, but it is often labeled as "OBD" or "Diagnostic." If the fuse is blown, replacing it should restore power to the diagnostic port. Always ensure the vehicle is off before changing any fuses for safety.
The fuse is located in the plugin terminal
its on the positive battery terminal, usually the tab breaks off, so fix this by buying a new terminal end, a waterproof fuse holder for the same style fuse and take the wire plugged into the terminal and cut the plug off and put the fuse holder between that and the terminal. that's how i fixed mine
the OBDII terminal is located on the driver side in the fuseblock panel. There is another diagnostic terminal located on under the the same dash panel just a little further under the dash it is a round terminal looks like something for Toyota to hook their scanner into. Then their is one under the hood about midway back and in the center on top of the engine that is for engine diagnostic . your welcome Jeremy Hadley Arab AL.
We have a 2002 2wd TB and I had the same problem i looked it up just like you and all of the online techs were saying look for 15amp (blue fuse) for cigar/power outlet found the fuse finally its in the fuse box under the hood on drivers side your looking for a 20a (yellow micro fuse) its about right in the center of the fuse block look at the fuse block schematic on the in side of the large outside cover its designated CIG on the cover.
The diagnostic port on that car should be next to or in the fuse box panel
fuse # 41 - 20 amp mini fuse - cigar lighter , diagnostic connector power