99 GC won't shift from low with low fuel

My 'Check Engine' light sparked up on my 99 GC Laredo today. It was still running the same so I didn't figure it would be a big deal to just take it in tomorrow. I was below a 1/4 tank but I can't remember whether or not the 'Low Fuel' light had come on before I got home. Anyway, I needed to make a short trip and when I started it up the 'Low Fuel' light came on. Then I couldn't get the thing to shift out of low gear. I was all over the internet trying to figure out why it wouldn't shift but definitely didn't relate the low fuel to the problem. Turns out I found at least 3 postings from victims of low fuel keeping their GC from shifting out of low. I made a quick, 20 mph trip to the gas station and it's shifting as it should. 'Check Engine' light is still on.
I'm thinking I need a flash update to correct this issue, but the posts from other victims all said that Jeep had no idea what might cause the problem. The posts were all at least a couple of years old so I thought somebody here might know if there is a solution from Jeep yet. Please respond if you have any info.

The dealer cleared up my problem, i think, with a new transmission speed sensor. Seems to make sense. I imagine the low fuel light & check engine light being on at the same time is what whacks out the TCM so that it won't shift.