Intermittently while at 50 to 55 cruising speed, transmission seems to go into neutral and the RPMs rise to 3,000 with no acceleration?

Tiny
NW1776
  • MEMBER
  • 2006 CHEVROLET TAHOE
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
Pull over to sit a min then continue on down road. May happen again, may not. More often than not it shifts as it should, all day w/no prob. No leaks, smells or noises. Less than 100,000 on new 5.3 motor and rebuilt transmission, done 5 to 6 years ago 250,000 on body. The problem started a year ago or so, but only done it, maybe once or twice a year. Last couple weeks it's gotten more frequent, but not every time it's driven. No codes relating to trans. All mechanic work has been done by cert. Mechanic at a seemingly reputable shop.
Saturday, April 20th, 2024 AT 10:02 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

Based on your description, it sounds like you have checked the basics. I suspect the fluid is full and clean. That leaves line pressure as a question. Is that something that has been checked? If the truck has a transmission cooler, it may be partially plugged causing issues.

There are three different things related to the line pressure, pressure control solenoid, fluid pressure manual valve, and the valve body. Of course, the filter can play a role in a pressure issue.

I attached diagnostics for testing pressure below. Take a look at them and let me know if that is something you feel comfortable performing.

Take care,

Joe

See pics below.
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Saturday, April 20th, 2024 AT 10:16 PM
Tiny
NW1776
  • MEMBER
  • 4 POSTS
Thank you, Joe. Will inform you of results this afternoon.

Kindest Regards,
Nick
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Sunday, April 21st, 2024 AT 6:56 AM
Tiny
NW1776
  • MEMBER
  • 4 POSTS
More like "this evening", huh Joe?

Line pressures are falling within acceptable ranges according to specs uploaded. Tahoe hasn't presented problem at all today. I just don't know. Maybe electrical? That's about only thing left? Pure D ass befuddled, I am.
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Sunday, April 21st, 2024 AT 6:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

LOL No problem on the timing. As far as what you described, it could be related to something electrical. The line pressure is controlled by sensors/solenoid valves.

Have you tried scanning the can-bus? There may be codes stored in other modules that could point us in the right direction.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know if that is something you have checked or if you can do it or have it done.

Take care,

Joe
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Sunday, April 21st, 2024 AT 6:55 PM
Tiny
NW1776
  • MEMBER
  • 4 POSTS
I have not performed that type of scan. But will look into getting one. Lol, to be honest, I never knew a "can-bus" scan/scanner even existed. Learn something new every day, that'll be a few more new folds in the ole dome. Thank you, Joe! Will post ASAP with any leads on prob.
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Sunday, April 21st, 2024 AT 7:23 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,068 POSTS
Hi,

You are very welcome. Things are becoming more and more complicated, so I assure you that you are not the only one.

Take care of yourself and let me know what you find or if I can help in any way.

Joe
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Monday, April 22nd, 2024 AT 8:04 PM

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