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My transmission is not shifting?

Tiny
IUREIS
  • MEMBER
  • 2010 CHEVROLET BLAZER
Problem: Upon slow acceleration, at any speed, the engine will drag and hesitate. The Service engine light will come on and then the car will not want to downshift or shift at all. When floored at this point, nothing happens. Acceleration is virtually zero. After stopping the car (say at a redlight), starting again it will refuse to shift into 2nd gear. When it finally does, it will make a hard "thunk" sound and the car will surge forward. If the car is stopped and turned off for awhile, everything seems to go back to normal. Faster acceleration keeps the problem at bay. Having the heat on will make the problem happen pretty quickly so I run without it (I layer up well).

Transmission fluid and filter have been replaced recently, as well as, the fuel filter, fuel system cleaning, oil and filter. The speedometer also sticks and jumps as well on longer drives but I haven't checked the other posts for that yet!

Long and drawn out but that's the best I can explain it. Thanks for any posts you can direct me to that I may have missed or advice.
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Thursday, February 8th, 2007 AT 6:38 PM

50 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Disconnect the TCC solenoid on the tranny and road test again to duplicate the problem. This guide can help as well.

https://www.2carpros.com/articles/automatic-transmission-problems

Please run down this guide and report back.
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Friday, February 9th, 2007 AT 6:41 AM
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Sounds like you might have gotten your moneys worth out of that trans. Have it scanned for codes. Usually when those trannies start having 2nd gear shift problems it time for a rebuild. There were a ton of updates to the valve body in those that pertain to hard/late 2nd gear shifts. Have it scanned first, get back to us and we can go from there. BTW what year Blazer?
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Friday, February 9th, 2007 AT 7:51 AM
Tiny
IUREIS
  • MEMBER
  • 3 POSTS
The ol' S10 ran fine today, of course. Yesterday, though, after being driven and doing it's usual surge, etc. I put it in park, idled for a sec and then put her back into gear. Wham. Really was quite a jolt and then the same shifting hard into 2nd. Again, though after resting awhile, it was great. FYI.

I'll check the codes again and see what I can find this time. Always runs great when it's being checked! Thanks rasmataz and 2CarPro Jack. I'll get back to you on what I come up with.
BTW, it's a 1994 S10. Thanks.
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Friday, February 9th, 2007 AT 3:51 PM
Tiny
IUREIS
  • MEMBER
  • 3 POSTS
Finally found a code checker for the S10! The code checker (Actron CP 9001) displays Code #22. The description given in the manual was. Throttle position sensor (TPS) signal voltage is low during engine idle OR Fuel cutoff relay circuit is open or shorted to ground.
Does this make any sense for the shudder problem? And how does that connect with the hard shift problem when the Check Engine light comes on? Thanks again.
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Monday, March 5th, 2007 AT 9:34 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
The throttle position sensor is like your throttle valve operated by vacuum with the old type tranny. The VSS vehicle speed sensor is the governor
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Monday, March 5th, 2007 AT 10:42 PM
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
The Throttle Position Sensor tell the ECM how much throttle you are giving it. There is a link at the bottom of main forum page for Auto Repair Manuals. Go there and you will find all specs and instructions to test your TPS
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Tuesday, March 6th, 2007 AT 7:52 AM
Tiny
JOE THE MARINE
  • MEMBER
  • 86 POSTS
  • 2002 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 174,000 MILES
After I start the vehicle and want to pull out of the driveway, it is the 3 to 7 second delay for the car to move and after I put it in gear, and it warms up, no problem. This only happy when the car sits all night and it's cold, otherwise it shifts in all the gears and drives like a new car. This only happens when it sits all night. Can you lead me on the right path, I know transmission shops will nail you to the cross on this, and also I have never change the fluid, because it's a beautiful pink and doesn't smell burned. Can I do this myself if it is a vacuum line? Which I already checked.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
STEVE W.
  • MECHANIC
  • 13,483 POSTS
Your issue is a common one with the transmission in that truck (and many other GM's that use the same 4L60E transmission). It is caused by the worn rings and hardened seals on the interior parts like the front pump and pressure control solenoid. When they get cold they get very stiff and bypass the transmission fluid instead of sending it into the proper paths and apply pistons. Once the transmission fluid and parts warm up they get a bit more flexible and the transmission works again as the parts start sealing like they are supposed to. The only real repair is to pull the transmission apart and replace the worn and hardened parts. You could opt for an already re-built unit but if you use a good re-builder they can add in the upgraded parts for your transmission and make it better than new. There are some fluids sold that purport to make the seals flexible again and make the transmission work again but I have never used any of them. They could help or they could make it worse.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
DOUG GIFFORD
  • MEMBER
  • 4 POSTS
  • 2001 CHEVROLET BLAZER
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 278,000 MILES
My transmission will not go into third or fourth gear.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Your transmission is in what is called limp mode and with your mileage it is probably in need of a rebuild. Have a transmission professional look at it for an opinion. Make sure the transmission fluid is full and not dark brown or black.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
DOUG GIFFORD
  • MEMBER
  • 4 POSTS
It is not brown or black it is red, but it does not smell sweet like I read it should, and it is full. I read something about putting an additive to it might help.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Adding an additive like Lucus can help
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
DOUG GIFFORD
  • MEMBER
  • 4 POSTS
Well okay, that worked thank you.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
CANDY SNYDER
  • MEMBER
  • 2 POSTS
  • 2001 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 175,000 MILES
Have to manually shift the gears because it will not go into third goes in first and second fine. But you got to bypass 30 going to regular drive was wondering what the for Auto 4 wheel drive was and what could be causing the problem? Replace one sensor in the transmission and that did not fix it. It was a sensor closest to the passenger side not the driver side.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

Were there any codes set in the modules? If so, do you remember it?

https://www.2carpros.com/articles/automatic-transmission-problems

When was the last time you had the transmission oil/filter changed?

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Roy
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
CANDY SNYDER
  • MEMBER
  • 2 POSTS
Yes, rotor cap. Just got the vehicle about a week ago.
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Got it.

Can you check for any codes?

I would start by changing the oil/filter in the transmission.

Roy
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Friday, April 9th, 2021 AT 7:10 PM (Merged)
Tiny
RACHEL JACKSON
  • MEMBER
  • 1 POST
  • 2001 CHEVROLET BLAZER
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 260,000 MILES
I was driving my vehicle the other day and I went to pass someone and as soon as I got into the gas peddle the trucks rpm went up but never changed gears it just raved up. So I let out of it and got back down to forty to forty five mph. It felt like I was not going the speed. And it do not have the muffler on it and it does not sound loud it is quite. What could be the problem? Please help.
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Friday, April 9th, 2021 AT 7:11 PM (Merged)
Tiny
STEVE W.
  • MECHANIC
  • 13,483 POSTS
If the rpms went up but the vehicle speed didn't the most common cause in that vehicle is in the transmission. The sun shell is known for failing, and with the mileage you list the clutches are probably worn as well.

As for it being quiet, probably due to the convertor. They dampen the sound quite a bit.
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Friday, April 9th, 2021 AT 7:11 PM (Merged)
Tiny
AKRAY65
  • MEMBER
  • 1 POST
  • 2000 CHEVROLET BLAZER
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 125,000 MILES
Old transmission was bad so I replaced with another used one. It bolted up the same and I am pretty sure I installed it correctly. But it shifts kind of erratically, like it does not know when it should shift. Each gear works if you try them one at a time, but when driving it shifts strangely. Any ideas?
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Friday, April 9th, 2021 AT 7:11 PM (Merged)

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