No its not stuck on, its stuck off. It does not illuminate briefly when you start the truck and thus will not pass a smog check in CA.
I'll be fixing this 1988 Ford Ranger P/U this weekend and having done some homework already, I still need a tip. As background this truck did have a problem where it just stalled out and wouldn't start again. That problem was traced to a wire harness that came loose and got burned on the manefold causing (at least) one of the wires to go open. Evidently the one needed to keep things running. That was fixed through visual inspection with a little help from a Ford explorer 1993 shop manual.
Now I suspect the check engine light problem is the same cause (open wire in harness) only I don't know which wire to trace. I checked several repair guides and none show the check engine light and what wire it is associated with it. If I could just determine the color and connectors it runs through this would be easy.
I'm not usually one to suspect conspiricy but really. WRT the ECC and associated sensors and idiot lights; Chiltons and Haynes only show a picture of some parts and say its too complicated to troubleshoot. OK expected. The FORD shop manuals for my 93 Explorer have a single page saying check the third manual (you don't have). The EVTM (electrical/vacuum troubleshooting manual) for the 84 Ranger (by ford again) shows most of the wires to the ECC but not the idiot light (check engine).
If anyone has the ECC repair manual for just about any ford truck (ranger, bronco II, Explorer in the 1983 to 1993 range you can probably determine the wire color for me.
Yes, I will check the bulb first. So far I have only visually traced the wire harness back to the ECC so it seems likely there is another open wire in there.
My second option is to trace the wire from the lamp back to the open using a signal tracer (triplett fox and hound). That will work but at the cost of more effort.
Does anyone have any insight as to why this indicator lamp would be excluded from most service manuals.