2nd gear only

[newdieselguy]

Ok guys i need some help here please? On my way home last night i noticed the volt guage was dropping as i was driving. I kept going hoping that i would make it home to take a look at it. As i was driving the voltage got as low as 9 volts and it was like the transmission went straight to neautral so i pulled off to the side of the road put the truck in park and then it did go into gear, but only 2nd gear. I drove home the rest of the way only about 25 mph for about 12 miles. Lovely ride. When i did get home i found that the positive battery cable on the passenger side battery had come loose. I tightened it up went down the road and still only 2nd gear. Are our tucks transmissions equipped with a limp mode? If so what do i have to do to reset it? Or do you think something is wrong with the transmission? I thank you guys in advance for any insight in this matter.

[bhelms22]

Pretty sure that the 4L80e has a limp mode, guessin thats what you have. I've had engines go into limp mode and reset them by unhooking the battery(s) and holding the brake untill all the remaining power is drained out of the system. Might work for trannies as well. If that don't fix it I'd look into the tranny control module, grounds and solenoids.

[newdieselguy]

I might have to rename my truck to Christine! LOL woke up this ,orning and started the truck up and everything was fine. just a pesky SES light which if it doesnt go off on its own i will have to reset it myself.

[Husker 6.5]

Check the codes before resetting the SES. Therein may lie some answers to your mysterious 2nd gear only situation. It may be linked to the low voltage putting the TCM and/or ECM out of operating parameters for voltage.

[BeelzaBubba]

Look for a code 75 to confirm that this is from a low voltage condition (8.6V or less). Default action of the TCM is to maintain second gear and prohibit convertor lock-up.