Transmission problems

[Smoky02]

2000 GMC 4.8 with 4L60e

Truck is completely stock, never really even driven hard, most of the miles are highway miles. Although for the last few thousand miles it jumps in and out of overdrive at speed. It shifts into every other gear just fine like it always has. I wondered if maybe this was something that I could fix myself with some kind of quick fix, or if this means that my trans is starting to go out.

Thanks in advance,

Brandon

[txarkitekt]

So it jumps in and out of 4th gear? Or the converter unlocks?

[Smoky02]

The converter unlocks

[txarkitekt]

Could be a number of things. A dirty MAF could be making you loose power, causing the converter to unlock.

But is it random times? While lightly accelerating when it shouldn't unlock?

The TCC solenoid could be going out. But if that's the case, you SHOULD get a CEL.

[Smoky02]

It actually pops out while accelerating like it's supposed to, but when riding normal or even in cruise on a flat highway it will lock and unlock. What is a TCC solenoid?

[txarkitekt]

Its the solenoid inside the pump (accessible by removing the pan) that activates the fluid into the TC to make it lock up.

If the solenoid is ok (which I am thinking it is), then the screens on the TCC solenoid may be clogged. If that one is, they all are. I would do a fluid change (not a complete flush), coolant line flush, a new tranny filter, and pull out each solenoid and clean the screens.

[Smoky02]

Is it possible that it's just the stock TC?

[txarkitekt]

The TC will lock up only when the solenoid pops. The verter should be good. Just drop the pan and do what I talked about earlier. Prolly could stand a fluid change anyways...

[Smoky02]

The fluid has been changed about 10,000 miles ago. But thanks, I'll check that out.