Trans slipping 2 to 3 shift.

[rustyp]

1996 Tahoe.

Trans started slipping when it shifts from 2nd to 3rd, if you let off the gas when it starts slipping it completes the shift, if you keep the shifter in 3rd it shifts up to 3rd normally.

Once in 3rd you can return the shifter to OD and it shifts into OD normally.

Changed fluid filter still the same.

Suggestions?

Thanks in advance.

 

[lesterl]

How many miles?

Valve body perhaps?

Worn pump?

You pull codes?

 

[rustyp]

How many miles?

Valve body perhaps?

Worn pump?

You pull codes?

I think the miles are irrelevant the trans needs CSIed to diagnosed and pinpoint exact problem regardless of miles.

Trans went from working perfect to having a problem over night suppose it could be a code, can you have a trans code without a light on the dash?

Thought I would ask here first to see if slipping 2-3 shift was a popular problem

Thanks.

 

[lesterl]

ok then

 

[rustyp]

UPDATE
Took my Tahoe to my buddies he read the codes it found P0724 and P0742 traced it to a bad brake light switch, installed a new brake light switch GM 93801734 the clip that holds the switch on was bad the part number on the bag was 15705042 he charged me 12 bux installed.

Further info on this trans problem, he has also seen about a dozen times over the years customers with the same trans symptoms and it turned out to be a dirty MAF sensor 90% of the time its autos with a K&N filter installed funny how when you drive a auto in 98 degree heat in stop and go traffic how that crappy oil on the K&N filters acts when you then hit the hwy and run 70-80 mph the K&N oil has then puddled on the bottom of the air box inner fender etc. allowing dust to then pass the filter OR the oil is sucked into the intake system and mucks up the MAF throttle body etc.

Hopefully this info will help others in the future if it happens again to me the FRIST thing I will check is if the brake lights work 100% of the time mine would not work about every 10th time you depressed the brake , next thing will be read the computer codes.

I will change the trans fluid again in 5k miles see how it looks.