Transmission shifting hard
CF Beginner
Joined: Apr 2012
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I have a 97 cheyenne and it shifts hard from 1st to 2nd. had it put on the machine at a shop and read code 1870. was told torque converter was overheating...maybe more probs would be discovered when they broke it down?? but here's the catch...it only shifts hard after i have ran it for a while. when i first crank it up it shifts PERFECTLY ! then after its been ran a while, it starts shifting really hard but ONLY into second ! any suggestions??
CF Beginner
Joined: Oct 2013
Posts: 11
Likes: 1
From: Buffalo, NY
This is a computer controlled transmission. There are no linkage adjustments. Just a plug and play. If its shifting hard, either the computer is telling it to for some odd reason or there is an internal problem inside the transmission. Get it scanned for codes. If no codes get to transmission shop. They may have to change the EPC solenoid on the valve body. A line pressure check should also be done.
CF Beginner
Joined: Jun 2011
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I just went through this with my 2002 Suburban. It had 373000 miles on it when the sun shield went. After the rebuild I got the P1870 code (transmission component slippage). I had the very hard shifts after driving a while. Anyway, the computer takes over and raises the line pressure to try and keep the transmission from slipping. I went on line and bought the sk 1870 shift kit to eliminate the P1870 code. Now it shifts a little firmer at all shifts and I can feel the converter when it locks up.
CF Beginner
Joined: Oct 2013
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I had a 2001 2500 Silverado 4x4 that took spells where it would shift like a drag car. This happened off and on for 3 years. Never threw a code other that a pressure switch which I replaced. During the hard shifting spells, the truck did not want to idle. The idle would fluctuate 3 or 4 hundred rpm. I cleaned the throttle body, replaced the IAC sensor, but it always came back. Finally, 2 months ago as a potential buyer was driving the truck it started that hard shifting crap. But this time it threw a check engine light. Put the scan tool on it and the throttle position sensor was out of range. The next day on the way to the shop the light went out and the shifting and idle was normal. Replaced the TPS and all was well. I guess the computer was seeing an abnormal idle and was boosting the trans. line pressure to prevent potential damage.
CF Beginner
Joined: Jun 2015
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Hard shifting trans.
Well from what I have read the thing about transmissions that have high milages and have never been changed and then you change it and transmissions starts to mess up is like this. Since the old transmission fluid has been in there so long then residue or crud has built up on the parts and changing it with fresh fluid and it having fresh detergents gets rid of this residue which could have prevented both internal and external leaks.
Also fresh fluids changes pressures and friction properties . Worn and well broken in clutches and seals sometimes don't like these changes. I havn't witnesed this personally by doing it but it did happen to a friend of mine and I just did a quick google search and came up with the info. in this post.
It's kinda like the high milage car/truck that has never changed the fuel filter and then right after the filter is changed the fuel pump dies.
Also fresh fluids changes pressures and friction properties . Worn and well broken in clutches and seals sometimes don't like these changes. I havn't witnesed this personally by doing it but it did happen to a friend of mine and I just did a quick google search and came up with the info. in this post.
It's kinda like the high milage car/truck that has never changed the fuel filter and then right after the filter is changed the fuel pump dies.
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Summett
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Feb 13, 2007 2:59 PM
