OBD2 Port, Cigar Lighter and Electric Mirror Power

A 550 owner on the Technical Q&A forum says he is getting low voltage to his OBD2 port (pin 16).

The wiring diagrams show power coming (basically) directly from the battery via fuse 21. However, he states:

On some cars, does the OBD2 port use a different fuse (which is powered by the ignition key, either directly or via a relay)?

According to diagrams and various sources, Fuse 21 on the 550 also powers the cigar lighter, dome and luggage lights and the trunk release. Do these also need ignition key power on some cars? I know on later model F355's, the cigar lighter power source was switched from battery power to ignition key power (using a different fuse). Is this the same on later model 550's? If so, what fuse is involved?

On later model 355's, the cigar lighter is now powered by the electric mirror and window heat fuse. On the 550, the window heat fuse is #18. However, I haven't been able to find a diagram which tells me what powers the electric mirrors. The 550 Workshop Manual doesn't mention a fuse for the mirrors.

Does the owner's manual specify what powers the mirrors? Or is it perhaps shown on the decal on the relay panel cover? I haven't been able to find a clear photo of the decal.

Thanks.

 

Thanks, Dave! Much appreciated. Looks like your decal agrees with the wiring diagrams. That is not to say your decal agrees with your car. My F355 decal doesn't agree with my car. Do you need to turn on your ignition to power the cigar lighter?

According to the parts manual, there was a decal change at vehicle assembly number 27151. I have no idea what month/year that was. Do you know if your assembly number is before or after that, Dave?

 

Thanks, Dave. That means that the decal change was probably made quite early and, if your recollection is correct, the decal change was unrelated to a change relating to OBD2 power.

Back to the drawing board...