LMM: Heart Attack Code P0777

[tirwin]

A month ago I bought an 09 LMM (Stock powertrain, 6"lift, no tune, only 54k miles) and have been noticing that the trans had been shifting a bit rougher than the 01 dmx I had a while back. A few times while accelerating fairly hard from gears 3 to 4 the trans would hesitate and seemed like the truck would die then pick back up again, I chocked this up to be (in my inexperienced mind) the turbo spooling at the same time as the trans shifting causing a delay in shifting and turbo lag. The other day, I hit the pedal just a little too hard and the trans dropped into limp mode ultimately leaving me on the side of the road holding up traffic for a good half hour. The truck had no problem starting or revving but the trans would not shift at all out of park. I finally left the truck off as I called AAA to come get me and then tried it one last time, it worked and seemed to be running fine. I took the truck straight to vato-zone and they ran the code (the dreaded P0777, Solenoid B stuck in position) and they told me it was probably due to dirty fluid. With only 50k miles on it, I don't see how the fluid could be dirty enough to cause this type of problem. I was planning on putting EfiLive on the truck but will not do this in fear of the trans not being able to handle any more power. Which of the following fixes would you recommend I start with to keep myself on the road.

1. Flush the trans and change the fluid

2. Drop the pan, replace the solenoid, have GM come and re-calibrate the solenoid to the ECM

3. After only one time in limp mode, have I damaged c3 and c4 to the point that a shift kit or rebuild is the only option?

I appreciate the help and I will continue to search the forum for further information into my case. Cheers! :beer

 

[56taskforce]

I will be pulling my transmission this coming week. It had limped with the 777 code twice I will let you know how it looks when I tear it down. It has been running fine since it limped as long as I stay in tune 3 or lower.

 

[Mike L.]

I find it hard to believe a lifted truck never had a tune. P0777 is a releasing clutch coming off too slow while an on coming clutch is applying. You had a tie up ( in 2 gears at once for a moment ) Could be a speed sensor or internal clutch damaged.

 

[jkholder09]

I have seen it in one truck where the clips that hold the solenoids and wire harness in had popped out. solenoid had slid back. Maybe its that simple

 

[onebaddmaxxx]

I have seen it in one truck where the clips that hold the solenoids and wire harness in had popped out. solenoid had slid back. Maybe its that simple

In the pressure its sustained to, i would think that within 6 years and 54k miles it would have popped a clip by now.

 

[DaJokr]

I find it hard to believe a lifted truck never had a tune. P0777 is a releasing clutch coming off too slow while an on coming clutch is applying. You had a tie up ( in 2 gears at once for a moment ) Could be a speed sensor or internal clutch damaged.

^^^^^^^^^^^^^^^

 

[tirwin]

I find it hard to believe a lifted truck never had a tune. P0777 is a releasing clutch coming off too slow while an on coming clutch is applying. You had a tie up ( in 2 gears at once for a moment ) Could be a speed sensor or internal clutch damaged.

The previous owner was an 84/yo man who put 8k miles per year on the truck, the dealer installed the lift before I bought it. I got a wild hare and decided to run a carfax on the truck, The original purchase date for the truck was Feb, 2010 so it turns out it's still under warranty for another month. I dropped it off at Chevrolet yesterday and we will see how it goes. For now i'm stuck driving my work truck (2014 f-150).... Blasphemy!

I appreciate all of y'all's help and will keep you updated on the status of the repair

 

[Mike L.]

In the pressure its sustained to, i would think that within 6 years and 54k miles it would have popped a clip by now.

It would never have thrown a 777 code with a missing clip.