Yes...that circuit is fused. I blew the fuse on my OBD II power circuit when using a power converter in the auxillary power port. Apparently my power port and the OBD II power circuit were wired in series. I found the fuse by looking in the owner's manual.
Tom
The "Service Engine Soon" light on my 1997 Econoline 150 4.2L has been
> coming on for hours/days and then going off.
>
> I've gone to AutoZone twice (when the light was on) and they don't get
> any output codes (the scanner does not come on).
>
> I don't have the owner's manual, and I was wondering if it might be a
> fuse? There is also no lights on/key in ignition chime - maybe the
> same fuse, or maybe it just doesn't have one?
>
> Any insights?
>
> TIA,
> Wallace