When changing the transmission fluid and filter should the transmission be flushed?

Tiny
BRICE CUMMINGS
  • MEMBER
  • 2008 BUICK LA CROSSE
  • 3.8L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 157,000 MILES
I just have a question. When changing the transmission fluid and filter should the transmission be flushed?
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Wednesday, September 28th, 2022 AT 10:08 AM

12 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

A few years back, that is all anyone would do to service the transmission. Then flushing became popular. However, flushing is not required when changing the fluid and filter.

Maybe I'm getting old, but that is the only way I still do it unless the fluid is extremely dirty. Take a look at this link. You may find it helpful.

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

Let me know if this helps or if you have other questions.

Take care,

Joe
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Wednesday, September 28th, 2022 AT 6:51 PM
Tiny
BRICE CUMMINGS
  • MEMBER
Thanks! I was getting conflicting advice. One friend said get it flushed and another was saying don t because it can loosen debris that can fall off later and cause problems.
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Thursday, September 29th, 2022 AT 3:37 AM
Tiny
BRICE CUMMINGS
  • MEMBER
I have another question. Can a bad throttle body cause codes for the traction control to be showing up?
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Thursday, September 29th, 2022 AT 3:57 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

As far as the throttle body, anything is possible, but it is very unlikely. What code did you get for the throttle body? Let me know so I can look deeper into the code.

Let me know.

Joe
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Thursday, September 29th, 2022 AT 6:26 PM
Tiny
BRICE CUMMINGS
  • MEMBER
I will send you the codes when I get them. The thing is first the regular check engine light came on and then the digital display that gives you things like odometer, fuel stats, tire pressures and traction control on/off displayed reduced engine power and then service traction control system.
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Friday, September 30th, 2022 AT 4:11 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

I'm wondering if there is an issue with a vehicle speed sensor. The codes should get us pointed in the right direction. As far as a speed sensor, if a wheel speed sensor fails, all the things you mentioned will likely turn on.

Let me know what you find.

Joe
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Friday, September 30th, 2022 AT 9:40 PM
Tiny
BRICE CUMMINGS
  • MEMBER
Sorry about the delay in getting back to you with the codes! Here they are: P0741, P1125, P1811, and P2138. I am hoping you can still see fit to help me.
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Wednesday, October 5th, 2022 AT 1:40 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Welcome back and absolutely I'll try my best to help. You are always welcome here.

DTC P0741 - Torque Converter Clutch (TCC) System - Stuck Off

DTC P1811 - Maximum Adapt and Long Shift

The aforementioned codes are specific to hydraulic pressure being applied to the torque converter clutch. To answer your question, the throttle position sensor certainly can contribute to this issue because the transmission control module (TCM) requires accurate information from the PCM to determine shift timing.

Codes 1125 and 2138 are for the accelerator pedal position sensors 1 and 2. The code is saying there is a difference in the signal voltage between the two which should be equal.

If you look below, I attached the diagnostics for the 1125 and 2138 which are tied together. I feel this is the place to start because it can be causing issues with the other components. If the TCM doesn't know the correct information from the throttle actuator control system, it won't know when to shift.

Take a look through the directions and let me know if you are comfortable performing them.

Take care,

Joe

See pics below Note: The last pic is simply showing the APP switch.
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Wednesday, October 5th, 2022 AT 6:43 PM
Tiny
BRICE CUMMINGS
  • MEMBER
Thanks for your help! I will let you know if the problem is remedied!
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Thursday, October 6th, 2022 AT 3:32 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
You are very welcome. Please feel free to come back anytime in the future. You are always welcome here.

Take care,

Joe
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Thursday, October 6th, 2022 AT 7:36 PM
Tiny
BRICE CUMMINGS
  • MEMBER
Thanks again for your help! I ended up having to put a new throttle body in and it is working so far! I will be sure to contact you in the future with any questions! You guys are very helpful!
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Thursday, October 13th, 2022 AT 5:33 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Thanks for that update. I'm sure it will help others. I miss the old days. LOL Things were much easier. I was able to listen to an engine or transmission and recognize what was wrong. It doesn't work that way anymore. LOL

Take good care of yourself.

Joe
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Thursday, October 13th, 2022 AT 6:40 PM

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