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Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 17004
Experience:  15 years GM master tech
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1997 Chevy: shifts..gears really hard..Automatic transmission..smooth

Resolved Question:

1997 Chevy Silverado PU 454 engine...Transmission periodically when it gets warm, shifts
into gears really hard, like it slams into each gear. (Automatic transmission). Let it cool
down and it works real smooth. Fluid is nice and red, does'nt smell. Changed radiator,
removed trany cooler and blew it out with air, seems ok. Still does it.
   Now one thing that did happen prior to this happening is as follows........Had a cooling
leak on the engine, loosing a fair amount of anti freeze before I discovered that, and
also had a tranny leak at that time, lost two quarts of fluid.
   Is it possible the tranny got to hot at one time, and broke down the tranny fluid?
Also, it appears that the fluid goes to the tranny cooler first and than to the radiator &
back to the tranny.Is that ok?.....Looks factory installed.
   Transmission filter changed 2500 miles ago. Any Ideas????????
Submitted: 8 years ago.
Category: Chevy
Expert:  Gary replied 8 years ago.
yes that sounds fine if the tranny fluid runs from the trans to the cooler then out of the cooler back to the the check engine light on?any codes?was the problem there before the tranny service?was the problem there after the service?
Customer: replied 8 years ago.

Yes the check engine light has been coming on periodically also.

I haven't got the code read out yet. Will do that next.

Expert:  Gary replied 8 years ago.
ok let me know what the code is..
Customer: replied 8 years ago.
I'll let you know soon.......
Expert:  Gary replied 8 years ago.
ok..and also when you reply back can you tell me if it is a 4L60 or an 4L80 trans,,
Customer: replied 8 years ago.
How would I tell what it is?
Expert:  Gary replied 8 years ago.
see if the trans pan is longer front to rear then side to side...or if the pan is same size or square
Customer: replied 8 years ago.

Hi....sorry i'm late on this........did a scan and a TPS sensor

code PO 122 came up. I don't think that has anything to

do with my tranny peoblem. Seems like when it warms up

the converter tends to wine or make a howling sound

and shift into gear violantly. No Engine check light or

anything. Than I can turn off the truck for a while and

it shifts nice and smooth. Again, I changed the radiator,

changed the t-stat....195 degrees. Thinking it could be

heat realated.'s a long pan from front to rear, on the tranny.

Expert:  Gary replied 8 years ago.
ok if you have a code p0121 the throttle position sensor is not working right and that can cause alot of engine and trans realy are going to have to fix the TPS code first
Customer: replied 8 years ago.
OK.......The code was PO that the same as PO 121??????
Expert:  Gary replied 8 years ago.
im sorry P0122 same code for TPS sensor..i misread..but it stil,l is a TPS code..there is a problem with the TPS
Customer: replied 8 years ago.

I'm changing the TPS this weekend, I'll keep you updated.

Will let you know asap.

Expert:  Gary replied 8 years ago.
ok let me know
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