Lost overdrive while going down hwy. Trny cooler line replaced yesterday. No problem shifting prior.

The line is likey a rubber hose, but some ****** cooler rubber hose and replace it with that.

You should not use overdrive unless you are steadily going highway speeds. I had one of those and my ex liked to use cruise control on windy coastal roads. This caused it to shift back and forth from 3rd to overdrive constantly. So I disconnected the cruise control so he couldn't use it. Lol. I'm not suggesting this for you. You should keep overdrive off for now and have your transmission serviced. New filter & oil & flush the cooler. Make sure you ONLY USE THE RECOMMENDED FLUIDS!!!!!!!!!! See if that helps. Do not use overdrive pulling a trailer and going up a hill and do not use it if you are on windy roads where you are slowing down alot of times. Try letting off the gas for a second when you do want to engage the overdrive. Remember to always check your automatic tranny fluid with the engine running and fully warmed up.

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Have the tranny fluid changed. may want to change the filter at the same time.

Check fluid level with engine running! Does it have or do you see fluid under,or all over the transmission?Refill if needed!

Sound like a trans problem. is this during hwy driving or city?

I think rebuild try and service it if you find any lining material in the pan bad news

Try changing the transmission fluid and transmission fluid filter. It is a fairly easy but kind of messy job. Just buy the new fluid and filter, Grab your metric socket set and go at it. NEVER WORK UNDERNEATH A HOT VEHICLE. You have to pull the transmission pan to do this job. When you break the gasket seal several quarts (liters) of transmission fluid will cascade down on you. Be ready for it. Don't forget that when it stops draining there is still a lot of fluid left in the pan. When you finish cleaning up the fluid clean the gunk out of the pan. Install the new filter and reinstall the pan with a new gasket. Do not over torque the pan or filter bolts. If you strip them out or break them off you will need professional help to repair it. Refill the transmission with fluid. It should take six or seven liters.

check oil level first, than check the electrical connector on the tranny. This sound like the transmission shifts from overdrive to drive. Check the wiring from the transmission to ECU and other items. If than happen again, check the shift cable, kick down cable. If that doesn't help, let the tranny be checked at a servicestation.

have a 1998 K3500 silverado 4x4 with 454 motor and 4L80E transmission. I can not get over 55 or 60 mph. At that speed the transmission down shifts from 4th (OD) to 3rd. The speedometer also drifts from about 50 to 65. If I try to speed up it will down shift to 3rd. I have replaced the VSS on the trasfer case. Is there another speed sensor somewhere? Or could it be the TPS? The truck drives and shift normal up to this point. where should i look next. thanks

I'm a big chevy fan and the reason it wont shift is because of the big tires.What happens when you put big tires on it and still have the same gear ratio the tires slow down the speed alot.There for making the trans seem its still going slower.The only real adjustments you can do here are first adjust the kick down cable if it has one,Next would be change the gear ratio to compinsate for the big tires.But if you have the elctronic trans theres really nothing you can do to adjust the kick down.But if it does this cable controls how the truck shifts on where the gas pedal is.To adjust the kick down cable you need to look at the cables that go up to the throttle likage.the cable thats on the bottom is the one you need.Next behind the bracket that holds the cable is a metal tab its actually in the cable.Push that tab in and the center part of the cable which looks like a con push that all the way in release the tab.Next jump in the truck and press the gas pedal to the floor now its adjusted.Thats all you can do..Hope this helps you and have a great day..

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