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Discussion Starter · #1 ·
2004 Enoy 4.2L 2 wheel drive. Driving over the sierra Nevada mountains my traction control turned off and would not turn back on. Vehicle seemed to be fine otherwise until we got into Reno and came to a stop and accelerated again. The vehicle now had a hard shift from from 1st to 2nd and 3rd. Stopped at hotel for about 1/2 hour and everything was fine again. No warning lights on dash. Only light was the track control being off. Any thoughts? Thank you!
 

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I'd start w/fuses first... there MAY be a corollary in a common fuse there. Wouldn't it be nice if it's just a fuse?

NOW..... on to scarier and more expensive things.....

If nothing is out of the ordinary in the fuses ..... then definitely perform a transmission pressure test. Your unit might be stuck in full pump pressure mode. This is activated in Reverse, manual Low and WOT.

Some GMs have a Tow Mode where it is on constantly.

THM pumps can get stuck in that mode... but usually it's a line pressure boost or feedback valve that's hung up.

1 to 2 and 3 to 4 hard shifts can be a broken accumulator spring in the 2-4 servo.... which is serviceable from outside the transmission case.... but unfortunately hard to access b/o the transfer case and floor pan clearances. Still.... with the correct tool.... it can be done.

Direct/3rd gear hard/harsh line shifts are not common unless line and or boost pressures are outta sight.

Just before you start cussing and wrenching...... run the pressure test after the fuse check first...

DIAGNOSE.... DIAGNOSE.... DIAGNOSE!

About the Traction Control..... possibly a bad BOO switch.... ABS failure (eg: tone ring, pickup, assorted wiring), fuse(s).
 

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Discussion Starter · #3 ·
All this makes sense. My assumption is a common circuit problem. But I doubt it is a fuse. Sense the problem went away and has not returned. Thank you. I wii get a good wiring diagram and take a look at the circuits. Thanks
 
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