I have a '91 4.0L Automatic. I've been able to get codes from it in the past, and until today I hadn't had a check engine light issue.
2 months ago a yoke strap busted, and since then I've been saving up the money / time to get an 8.8 installed. I started it up today to move it (I've been starting ti up every week or so and letting it idle for about 15 minutes during the same time I start up my boat.) I started it up today, started fine. Drove it the 10 or so feet that it needed to go when I realized the check engine light had stayed on. Any attempt to retrieve failed. (See picture)
I disconnected the battery for about 10 minutes. When I reconnected it, I got error codes (12, 33 -- which are normal) and nothing else. I started and it, again, had no check engine light. I turned it off. Came back to it a few hours later and the check engine light is back on. And, again, any attempt to get the code(s) doesn't work.
Anyone have insight?
EDIT:: From what I can gather, it's running fine. I don't have any of my tools here to test fuel pressure or anything similar. But everything seems to be working..?