Loss of power- does not die completely but loses all gears

[Heavychevy23]

I have a 2010 Tahoe 5.3 4WD

I ran it out of gas the other day (I know I shouldn’t push it as far as I did)
Friend brought me a gas can, put enough in it to get me to the gas station. Was driving it home (45 minute drive) and it did fine until about 5 minutes from the house. Then it started bucking and misfiring.. parked it and went to work the next morning (30 minutes) made it almost there (I could see the building) and it went in limp mode.. engine was still running but would no longer accelerate. Put it in reverse and nothing.. turned it off and back on.. shifted normally. Made it to work and when I left for the day, I got about 10 minutes down the road when it did it again.. left me on the side of the highway.. I tried turning it off and back on and it would only go for about 30 seconds and do the same thing all over again. I was stuck on the highway for 2 hours waiting on someone to come tow it home..

Had a mechanic come out and plugged it up to the computer.. the only code it threw was “transmission fluid pressure switch low voltage” he said it was the alternator.. swapped that and it drove fine for 10 minutes and started acting up again.

I have been told it’s probably a bad transmission.. but if that were the case, I wouldn’t regain gears at all right? It shifts perfect until the engine warms up.

I’m thinking maybe fuel pump/filter but can’t find anyone who’s ever had similar issues to this.. I don’t have a ton of cash to troubleshoot and guess with repairs and this is mine and my husbands only vehicle at the moment. Any suggestions/ recommendations?! I’m at a total loss

 

[Fless]

Based on what you've said, I'd suspect the fuel pump, but that's a long distance guess. However, it's easy enough to "rent" a fuel pressure gauge from your local auto parts store in order to test the fuel pressure -- especially when the issue is happening. Many auto parts stores will rent the gauge, taking a credit card deposit when you pick it up, then crediting the deposit when you return it.

 

[Fless]

Another suggestion is to evaluate the transmission fluid level and condition. If the transmission hasn't been serviced lately, a check of the fluid to see if it's still red, or had turned brown/dark, would be a good idea.

 

[Heavychevy23]

The fluid is dark red with a gray/brown tint

 

[j91z28d1]

I feel like ice read that code before on there. maybe do a search on Nick's 6L80 thread?

if the switch is replaceable by dropping the pan. might be worth a shot?