p1870 code after diff swap
 

Recently had my 1999c5 in for a 2.73 -3.42 diff and i also had a mild tune for the new shift points and rev limiter the problem is that after a while of normal driving the trans comes out of lock up while in overdrive and starts building heat I've seen where the PWM can be adjusted to keep this from occurring, Can i get some advice on this subject matter and I'll pass it on to my tuner guy Thx...

Welcome to the forum.

Does he know why it's coming out of lock up after normal driving?

My tuner thinks it's high trans temps, but i don't think so because it will come out of lock up at 185-190 degrees but it takes approximately 1.5 to 2 hours of interstate driving before it codes He also thought it maybe defective trans components , then again 70k of adult miles i kinda doubt it.. thx for the reply 73 shark