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RPMs rev up high and shifts rough?

Tiny
JACOB MARINO
  • MEMBER
  • 2003 GMC SIERRA
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 260,000 MILES
What the subject says. Driving off in the first gear it drags out the RPMs and then shifts really rough. All the gears do it but first is the worst. Seeing as it’s an older truck I wouldn’t be shocked if the tranny was going but just wanted a second opinion. Also, another issue but not as important, it won’t shift out of 2nd and says service 4wd. Any common causes I can start crossing off? Let me know if you have questions!

Matt
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Monday, July 29th, 2024 AT 7:24 PM

19 Replies

Tiny
KEN L
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It sounds like the input shaft sensor is not working but we should run the codes to see if any are stored.

Here is a guide to help us:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is the location of the sensor and how to change it out in case there is a code for it. Can I ask if the speedometer is working? Please start a new question for the 4wd light flashing. Check out the images (below). Please let us know what happens.
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Tuesday, July 30th, 2024 AT 11:00 AM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
The only codes are some exhaust codes. The Speedometer works but he switched out the cluster before I bought it a year or so ago so it’s off by 5 mph. I can try to send a video of exactly what it does when it wants to shift if that would help.
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Tuesday, July 30th, 2024 AT 11:04 AM
Tiny
KEN L
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Yes, a video will help me see what's going on. If you have exhaust codes, you could have a partially clogged catalytic converter or a weak MAF sensor. These will make the PCM think there is less vacuum in the engine so it thinks you are going up a hill which will make the truck shift late.

This guide can help:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please go over this guide and get back to us.
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Tuesday, July 30th, 2024 AT 1:08 PM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
I’m checking out the article now but here’s the videos. It’s hard to hear but I have to give it more gas for it to actually shift or it’ll just drag out a few seconds longer.
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Tuesday, July 30th, 2024 AT 4:17 PM
Tiny
KEN L
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Yep, it is shifting late, did it shift late with the old cluster? Thanks for the videos, they help.
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Tuesday, July 30th, 2024 AT 4:22 PM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
I think I remember him saying it did but I have no way of knowing for sure. I bought it over a year ago and have moved since, sorry.
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Tuesday, July 30th, 2024 AT 4:24 PM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
Reading through the article there is a part about a rattling in the exhaust system. There is a rattle when the RPMs reach about 1800-2300 RPMs that I’ve never been able to find.
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Tuesday, July 30th, 2024 AT 4:29 PM
Tiny
KEN L
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This could be the catalytic converter has fallen apart internally which will create the rattle.
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Wednesday, July 31st, 2024 AT 9:30 AM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
Would that cause the transmission problems as well?
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Wednesday, July 31st, 2024 AT 9:38 AM
Tiny
KEN L
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Yes, it will make the transmission shift late.
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Wednesday, July 31st, 2024 AT 11:44 AM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
Okay, so if I disconnect the exhaust and cats from underneath, it in theory should run a little better, correct? I can test that when I’m home later tonight.
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Wednesday, July 31st, 2024 AT 11:54 AM
Tiny
KEN L
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Yes, that is part of the test in the guide.
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Wednesday, July 31st, 2024 AT 12:03 PM
Tiny
JACOB MARINO
  • MEMBER
  • 43 POSTS
So, after much looking, I saw that the previous owner cut the cats out and clamped pipe in its place. That’s what the rattle was, was a loose clamp. Is it still possible for the tranny problem to be an exhaust issue? It still has the muffler.
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Thursday, August 1st, 2024 AT 7:50 PM
Tiny
KEN L
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It is possible, if you disconnect the exhaust from the muffler and drive it you should know if that was the problem. Also, I would try the input shaft speed sensor. Can you tell me which exhaust codes are coming up?
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Friday, August 2nd, 2024 AT 9:25 AM
Tiny
JACOB MARINO
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Yeah, it’s a P0157 and P0332 are my only codes but the 0332 is a knock sensor. I can’t remember if there was a disconnect before the muffler that’s somewhat close but if there is I’ll try it when I get back.
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Friday, August 2nd, 2024 AT 9:59 AM
Tiny
JACOB MARINO
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  • 43 POSTS
Also, would the 03 have an input shaft speed sensor? I know they were introduced in 04. Where would it be?
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Friday, August 2nd, 2024 AT 10:12 AM
Tiny
KEN L
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Yep, these should not affect the transmission shifting.

P0157 - O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2):

P0332 - Knock Sensor 2 Circuit Low Input (Bank 2):

The input shaft sensor is in the image below, if this doesn't work I would disconnect the instrument cluster and drive it to see if it is causing the problem. Check out the images (below). Please let us know what happens.
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Saturday, August 3rd, 2024 AT 10:17 AM
Tiny
JACOB MARINO
  • MEMBER
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I disconnected the cluster and it still ran as bad. I went to look for the speed sensor and it’s blocked by the front driveshaft, the exhaust, and a scrape plate. I might just have it sent in for a rebuild because there is problems with the tranny, 4wd, and it’s leaking oil so bad it’s almost impossible to get the bottom clean enough to see anything.

Thank you for your help but this one is just beyond me to fix. I really appreciate your time and patience!
-Matt
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Saturday, August 3rd, 2024 AT 5:52 PM
Tiny
KEN L
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Thanks for letting us know, we are here to help, please use 2CarPros anytime. Please let me know if you find a solution.
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Saturday, August 3rd, 2024 AT 6:17 PM

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