Transmission only shifts at high RPM's

Tiny
VICMIDD
  • MEMBER
  • 2000 CHEVROLET MONTE CARLO
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 189,000 MILES
Shifts at high RPM. The higher the gear the faster I half to go to get it to shift. That of course causes the RPM to get very high before it will shift. I half to push 90 mph at 3,400 give or take to hit final gear. First I hit 30 to 35 mph at almost 3,000 rpm before it will shift. Also causing horrible gas mileage. Not to mention most likely we're on the motor. I had change the intake gasket and cover. MAP sensor, throttle position sensor, temperature sensor, and idle control sensor. It used to idle high on the start. But since I changed those parts the idle is good but still shifting at high RPM.
Thursday, September 17th, 2020 AT 7:47 AM

28 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good afternoon,

Did it do this prior to the repair?

Do you have a scan tool that can tell me the voltage of the throttle position sensor at closed throttle?

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

Roy
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Thursday, September 17th, 2020 AT 9:14 AM
Tiny
VICMIDD
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I have access to scan tool. I do not have one. It would take me a day or so to access it. I do have test meter. The first TPS I bought was bad. This one is reading right around 5v. Which tells me it's good. I have OBD tool. I have code p0481 which I know is fan. I have code Po141 which is bank One O2. I also have TPS code which is P0122. But I believe that is still there because I haven't cycled the car enough for it to read the new TPS.
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Thursday, September 17th, 2020 AT 9:33 AM
Tiny
VICMIDD
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I'm not very keen on transmission. But I wonder if the torque converter is not locking?
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Thursday, September 17th, 2020 AT 9:36 AM
Tiny
VICMIDD
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Sorry that was supposed to say 11.5 volts.
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Thursday, September 17th, 2020 AT 9:42 AM
Tiny
VICMIDD
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Okay, my voice text messed it up. 11.5 from the battery and 5 volts to the TPS sensor so I know it's good. Sorry about that so many messages.
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Thursday, September 17th, 2020 AT 9:46 AM
Tiny
ASEMASTER6371
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Okay, first, if you have 11.5 volts from the battery, your battery is completely drained and I would charge it..

I attached a wire diagram for you to view of the TPS. What color wire did you test and found 5 volts?

The gray wire should have 5 volt reference.

I need the voltage from the dark blue wire at closed throttle with the key on.

https://www.2carpros.com/articles/how-to-check-wiring

Can you test that for me?

Roy
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Thursday, September 17th, 2020 AT 10:29 AM
Tiny
VICMIDD
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Battery was just about drained out. But good now. I still get 00.05 from dark blue wire. And 23.6 from blue wire with black line. With key in on position but not running and throttle closed.
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Thursday, September 17th, 2020 AT 2:45 PM
Tiny
ASEMASTER6371
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Okay, let us start over.

You need to back probe the dark blue wire with the key on. You should have, 5 to.75 volts.
When you open the throttle, it should rise to 4.8 smoothly.

Test that and let me know.

Roy
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Thursday, September 17th, 2020 AT 3:40 PM
Tiny
VICMIDD
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As soon as I get off work today. I will do that.
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Friday, September 18th, 2020 AT 8:38 AM
Tiny
ASEMASTER6371
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Sounds like a plan.

Keep us updated.

Roy
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Friday, September 18th, 2020 AT 8:40 AM
Tiny
VICMIDD
  • MEMBER
  • 18 POSTS
So here is video with key in on position and car not running. Yesterday I had steady readings. But now battery is at 100 %. I'm thinking I will buy role of proper wires and collars. And just re run them with new plug. Then check. If you think that's good idea. I have two different voltage testers and they're both doing the same thing batteries may be low in them so I'm going to change those batteries and try that before I do everything else. But what do you think about this video?
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Friday, September 18th, 2020 AT 4:12 PM
Tiny
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The reason you have no readings is because you have the connector disconnected.

Put the connector back on and back probe as I stated in my previous response. You will get no readings with it disconnected.

Roy
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Friday, September 18th, 2020 AT 4:19 PM
Tiny
VICMIDD
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It was not disconnected. It was on the battery ground. I couldn't hold both and roll throttle. Does that make a difference?
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Friday, September 18th, 2020 AT 4:24 PM
Tiny
ASEMASTER6371
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You had the connector in your hand. That is disconnected from the TPS. These checks are done with the connector connected to the TPS and you back probe the wires.

Roy
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Friday, September 18th, 2020 AT 4:28 PM
Tiny
VICMIDD
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As you can see I have a dark blue wire next is a light blue wire with a black line it could be great. Then there is a green wire then there is a green wire with a black line. Your diagram shows black wire and opposite end of blue wire. So I use the green wire with a black line on the opposite end from my blue wire for my positive and negative on the meter I still I'm getting different readings. One time is jumping up and down the next time it's showing 1.49 another time it's showing 0.01. I cannot get an exact reading. I also tried grounding my meter 2 a bolt on the body of the car with vice grips and to the battery and I get the same thing all over the place.
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Friday, September 18th, 2020 AT 5:14 PM
Tiny
VICMIDD
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I have 2 Monte Carlo SS's. One I'm working on is a 2000 my other one is a 2004 this is a picture of the two thousand four wires they are blue in green same as on my 2000.
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Friday, September 18th, 2020 AT 5:17 PM
Tiny
VICMIDD
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Sorry picture didn't load. Here it is:
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Friday, September 18th, 2020 AT 5:19 PM
Tiny
ASEMASTER6371
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Check the battery in your voltmeter.

You should be able to read at least the 5 volt reference.

Roy
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Friday, September 18th, 2020 AT 5:30 PM
Tiny
VICMIDD
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Yes, like I said I'm going to get new batteries for both of my meters. Because they are both doing the same thing. I don't think it's coincidence but we will see when I put new batteries in them tomorrow can't get out tonight. Thank you talk to you then.
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Friday, September 18th, 2020 AT 5:42 PM
Tiny
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Sounds like a plan.

Roy
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Friday, September 18th, 2020 AT 5:51 PM

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