New Transmission Slips just like the old one...!

[Andrew Bynum]

I have a 2004 Tahoe, 4.3L, 4WD, and a 4L60E transmission.

The original got almost 216,000 miles on it then started slipping...finally lost it.

I installed a rebuilt.

The rebuilt is slipping too. Just like the original transmission just before it cut loose.

Fluid is fine. I started in the middle and poured in ounces until it was almost dead on the top line.

When I activate the towing-switch, it doesn't slip at all.

Can the transfer case have anything to do with slipping? (It's the only thing I haven't replaced underneath.)

Any other thoughts?

 

[MadDogDelpho]

The fact that it is acting exactly the same makes me think that it might have something to do with the onboard computer.

 

[Andrew Bynum]

That has been mentioned before. A transmission guy suggested the original computer needed to be replaced.

Is it the main computer, or does the transmission have its own?

Thank you for the quick reply!

 

[rockola1971]

PCM takes care of tranny and engine. It could also be a problem in the valve body that was not corrected when the tranny was rebuilt. I assume you meant it has a 4.8l NOT a 4.3l. What gear(s) does the slipping happen? Towing mode switch just keeps transmission from hunting back and forth from 3rd to 4th when loaded down with a trailer at highway speeds.