Wheels not responding to the accelerator pedal, limp mode?

Tiny
WILLYHNDRXX
  • MEMBER
  • 2012 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
Car will start up just fine and drives good for about 3 minutes and then car goes limp all you hear is motor accelerating and no wheel response, but once I turn off the car and unplug the battery and plug it back up and start it car while be just fine again for about 3 minutes and goes in limp mode.
Saturday, December 7th, 2024 AT 2:59 AM

8 Replies

Tiny
AL514
  • MECHANIC
  • 4,781 POSTS
Hello, when the fault happens again, before you unhook the battery, have a full system scan done with a capable scan tool, you need to see what trouble codes are setting, if it's going into limp mode there will be codes stored in one of the vehicles modules. You will probably have to take it to a shop to have the entire vehicle scanned, meaning all the modules throughout the vehicle, but just write them all down, so we can help. You're erasing the memory every time you unhook the battery and therefore clearing out the current codes.
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Saturday, December 7th, 2024 AT 10:32 AM
Tiny
AL514
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Once we have a list of the codes that are set and in which modules, we can give you further directions. But it's very important to write every single code down, make sure to tell the shop if you don't have a capable scan tool. A basic OBD2 scanner that only reads engine control module codes will not be able to detect every fault happening. It's going into limp mode because of either a safety issue or to prevent damage to components.

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

https://www.2carpros.com/articles/can-scan-controller-area-network-easy
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Saturday, December 7th, 2024 AT 10:36 AM
Tiny
WILLYHNDRXX
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Codes are p0741 and p0700.
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Sunday, December 8th, 2024 AT 7:05 AM
Tiny
AL514
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Okay, sorry for the delay, P0700 is the transmission control system code, and the P0741 is the "Torque Converter Clutch Circuit Performance or Stuck off". I will post further information on these codes, but this sounds like a transmission issue. One quick look in service info states to check the condition of the transmission fluid, see if it smells burnt or is dark in color.
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Sunday, December 8th, 2024 AT 12:26 PM
Tiny
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Is this the 5.3 liter engine?
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Sunday, December 8th, 2024 AT 12:26 PM
Tiny
WILLYHNDRXX
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  • 3 POSTS
Yes. It's a 5.3 L V8.
My best guess "current me if I'm wrong" would be cleaning or replacing the Torque Converter Clutch Solenoid?
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Sunday, December 8th, 2024 AT 1:53 PM
Tiny
AL514
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Well, I would do some testing first, such as watching some live scan tool data for that solenoid and see how many and what data PIDs there are for it. The next thing you could do, and I'll have to check a wiring diagram first, but you could check the solenoids resistance to see if it's an open circuit inside the solenoid. I will look up the wiring diagram and service info for you.
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Monday, December 9th, 2024 AT 9:16 AM
Tiny
AL514
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In service information for the P0741 code, the first thing listed after verifying the code comes right back which it does in your case, The testing section in diagram 2 below is for a more intermittent type of fault but it sounds like the problem happens right away, you should still do a visual check of the wiring to the transmission for any broken or damaged wires, corroded connectors, etc. There is a 16 pin connector you will see at the rear of the transmission housing.(Diagram 10).
Then the next step is they have you run a transmission line pressure test (Starting at Diagrams 3-8 below), which is what would be done in many cases for transmission codes.

Some possible faults are also listed, But if there are no wiring issues found external to the transmission, it would be important to do a line pressure test to make sure there is adequate pressure in the transmission, the pressure can range from 45psi to 300psi,
Even though the code is a a torque converter clutch pressure code, there are too many other possibilities to just change the solenoid out.

A line pressure gauge taps into a side port on the transmission, so there's not much of having to take anything apart for the test,
They have you bi-directionally control the transmission line pressure with a scan tool which will help to reduce the fluid from overheating.

The manufacturer wants the line pressure test done 3 times in Park or Neutral. You will need a capable scan tool that has this pressure increase and decrease function to run this test. But it is the correct way to check the transmission, if there's low line pressure, diagram 9 goes on to list High- or Low-pressure causes,

There is a section for testing the resistance of each solenoid, but I spoke too soon on checking the resistance of the lock up solenoid being that is it part of the valve body, it's not something that can be done from the main electrical connector of the transmission, it looks like there is even a procedure for removing and reinstalling the electrical connector sleeve that runs to the valve body. This is something I would recommend a shop doing since it is a complex setup, And the Reset Transmission Adapts procedure needs to be done as well so the control module can relearn each shift pressure value.
Sorry for the delay, there was a lot of service information to go through.
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Monday, December 9th, 2024 AT 11:27 AM

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