'02 Tranny Issue

[runwideopen]

Hey Everybody,

I'm new here and hoping to get a little help. Have an '02 Suburban with 64k on it. Runs, starts and goes down the road great. Had it for about a year, bought it with about 45k on it from a dealer so I don't know any of the history. When I'm driving it around 45 mph it will sort of kick into Overdrive, RPMs go up two or three hundred, then it goes back down, mostly going up a hill but some times on more level ground. And it will sort pulse up and down a little bit. It will even do it when I run it in 3rd gear. Doesn't feel like a slip and it doesn't shift hard and it only does it around 45 no where else. It's more of an annoyance and a concern for me than anything. Fluid and filter in the tranny has not yet been changed, the last time I took it in for an oil change they said the fluid looked good. Only towed with it once for about 800 miles, don't know about before that. Would like some insight if anyone has any, if the tranny is going to puke on me I'd like to know, if I gotta live with it without spending a bunch of money and it will be fine that's fine too.

RWO

[taillight]

What size engine ?

[runwideopen]

5.3L. Haven't had any engine issues but I know that with the way things are with all the electronics and stuff that they work hand in hand, so maybe it's not really a tranny issue.

RWO

[taillight]

The 5.3 should not kick down on level road. Pull the trouble codes and see if the computer see anything that could be down on power.

[2000CAYukon]

Sounds like the Torque Converter Clutch is Unlocking after it Locks up. This can be due to a worn valve body.

If you touch the brake pedal (enough to turn on the brake lights but not enough to slow you down) it will unlock the torque converter. If the problem no longer happens while the brake pedal is slightly depressed, then the issue is most likely the TCC Apply Valve or TCC Regulator Valve in the valve body.

//2000CAYukon