Well, I hop in my truck to get lunch, and my 3rd and 4th gear would not engage.

Totally thought I lost the tranny. Get back in, and everything shifts fine now. 3rd/4th work, no slipping, and the lock-up for the T/C engages smoothly.

I've noticed that my low beams are always on regardless if I turn them on, while my DRL lights are off.

When I lost 3rd/4th today, my DRL lights were on, and my headlights were off unless i turned them on.

I've also been having issues with my CEL coming on for O2 sensors, then going back off. Also ABS and brake lights come on....then go back off.

Any idea where I should start?? Thanks!

 

I also might add that i checked the tranny fluid and it's clean and does not smell/look burned at all. Very clean looking.

 

It sounds like you might have a grounding Issue. Go over all the grounds and make sure they are clean and making good contact.

 

Transmission lost all gears today. Limped it into a parking lot. Shitty deal.