I have a 2001 Pontiac Grand Prix Gt. When I am driving on the highway at 100kph the rpms are at 3100. I have a feeling that it isnt shifting into overdrive and was wondering what the problem could be.
This trans is the 4T65E. It needs a 4th clutch hub. The splines strip off around 120k or more because they weren't hardened from the factory. The new ones have the hardened splines. The trans needs to come out and be partially torn down. I've fixed alot of these. Change the EPC solenoid while you are there. They wear and hang up causing intermittent harsh shifts
You can drive them forever without changing the hub but you'll never have 4th gear
I just fixed the same problem. This happened to me back in Sept. I was driving behind somebody uphill, about 45MPH, and I heard a "chirp", the tach increased and I list OD. I took it to a trans shop, they did a elec. check, and told me I lost the 4th clutch hub. This is so common, he grabbed one off the shelf to show me. I finally saved enough money and took it out myself. He rebuilt it in 1 1/2 days. Cost me about $900. But that was with a new convertor, and some shims, and the EPC, and with $300 of that being labor, got it back in a day. The car had 140,000 on it when it happened. Now I have to replace the front wheel bearings again for the 3rd time....
Basic Troubleshooting:
Although the Indicator says the vehicle is in "D" or "OD", is it really? If the linkage is mechanical, you may actually be in "3". Make sure the car is in neutral and pull the lever into the first forward position without looking at the indicator.
Does your vehicle have a switch to turn the OD off and you didn't know it? You may have inadvertently done this. In this case, though, usually there is a little dummy light on the dash that says "O/D off" or something like that.
Check the transmission fluid level on your vehicle and make sure it is to factory specification.
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I did try putting the tranny in neutral and then in the first available gear and still does the same thing. I just had the tranny fluid and filter flushed and changed so it would be at the proper level. So I dont think thats it. What all happens is when I am on the highway traveling at highway speeds is that the rpms will be at 3100 or so but when I let off the gas the rpms will drop to 1800 where they should be according to my manual but as soon as I give it some gas it will jump back to 3100rpms I also tried when I am traveling in OD to downshift to 3rd to see if I have any incress in rpms or to see if I can feel the tranny shift but nothing happens which leads me to think that my tranny stays stuck in 3rd.
i have the same problem--wont upshift out of 3rd into overdrive and rough going through the gears but its not the transmission--i'm perplex
what about the transmission temperature sensor? I believe there is a sensor that will keep it from O/D when the fluid is below a certain temp. Lupe
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