4L65 Lockup Shudder

[JamesTheDenali02]

I have a 02 Yukon Denali XL with the 6.0 lq4. I've been having a weird shudder when it tries to come out of lockup or shift down that almost feels like axle hop or something! I had a 4l60e in, figured it was the converter, and swapped it out along with a spare 4l65 out of an 04/05 Denali with full flush, new filter, and swapped my 2-4 corvette servo in. When I got the spare, I noticed it had fluid coming out of the pins on the large round plug under the lines on the passenger side. Because of this, swapped the internal harness from old trans to new one. Its running, driving, and shifting well, but I still have that weird lockup shudder! Rear end? Lockup solenoid? Bad luck and another junk converter?

UPDATE!!
Was still having problems with the part throttle shudder at that certain speed, and on the scanner everything looked perfect transmission wise, so decided to move to engine data. No set misfire count or codes, but with a passenger looking at live data while doing the bucking, cylinder 3 misfire was all over the place, only under part load at that certain speed. After further inspection, plug was cracked in cylinder 3. That was the entire problem, now runs and drives perfect. Stupid mistake, but so glad it works. (oops)

 

[stutaeng]

Does it do it around the 45 MPH range? It feels like a rumble and makes your mirrors vibrate slightly?

My 99 Silverado used to do that. I believe it was the TCC valve wear on the valve body bore?

 

[JamesTheDenali02]

Does it do it around the 45 MPH range? It feels like a rumble and makes your mirrors vibrate slightly?

My 99 Silverado used to do that. I believe it was the TCC valve wear on the valve body bore?

Yes!! Always around 50 mph. Does that mean I should look into changing the TCC or whole valve body as well?

 

[stutaeng]

Yes!! Always around 50 mph. Does that mean I should look into changing the TCC or whole valve body as well?

I've never been inside a 4L60e myself, but I believe your options are to ream out valve body and install an aftermarket valve to fix this issue. Or a remanufactured valve body. There's a spring you can install on that valve (basically will make the PWM into a on-off operation), but I've read if the transmission is throwing a P1870 code, this is no longer an option. But if it's not, then the spring is the cheapest option for like a $5 spring.

Watch this video. I bet it's discussed:

You may want to reach out to Nick at Nicktransmissions. He's a member at TahoeYukon Forum, and I believe there's an email on his YT channel to ask him questions.

 

[JamesTheDenali02]

I've never been inside a 4L60e myself, but I believe your options are to ream out valve body and install an aftermarket valve to fix this issue. Or a remanufactured valve body. There's a spring you can install on that valve (basically will make the PWM into a on-off operation), but I've read if the transmission is throwing a P1870 code, this is no longer an option. But if it's not, then the spring is the cheapest option for like a $5 spring.

Watch this video. I bet it's discussed:

You may want to reach out to Nick at Nicktransmissions. He's a member at TahoeYukon Forum, and I believe there's an email on his YT channel to ask him questions.

Thanks a lot I will totally look into this!

 

[AuroraGirl]

i feel like 2002 and 2005 may not have the same pcm controls 100% , i could be wrong

 

[Marky Dissod]

02 definitely controlled by P01, mechanical cable throttle.
05 controlled by p59 (I think), electrical signal throttle.

 

[ORVietVet]

02 definitely controlled by P01, mechanical cable throttle.
05 controlled by p59 (I think), electrical signal throttle.

Seems I see, on here and at TYF, more and more TPS and harness connector problems and the actuator on the throttle pedal causing problems. On my 2005 Tahoe, I expected problems eventually and knew I was going on a 5k+ miles trip in 2022 and I replaced both.

 

[JamesTheDenali02]

02 definitely controlled by P01, mechanical cable throttle.
05 controlled by p59 (I think), electrical signal throttle.

mine is a weird 02 and 1/2, came with drive by wire intake

 

[Marky Dissod]

02 definitely controlled by P01, mechanical cable throttle.
05 controlled by p59 (I think), electrical signal throttle.

mine is a weird 02 & 1/2, came with drive by wire intake

Even though it's usually true, I apologize for the generality.
Do you know which pcm your vehicle uses?

 

[JamesTheDenali02]

Even though it's usually true, I apologize for the generality.
Do you know which pcm your vehicle uses?

I don't unfortunately. Is that something I can find out from the RPO Codes? Or just have to take the cover off and look?

 

[Marky Dissod]

Looking at your sig, odds are (cannot guarantee) that
your '02 likely has a mechanical cable throttle, so your '02 PROBABLY has a P01, aka 12200411.
your '05 likely has an electrical signal throttle, so your '05 PROBABLY has a P59, aka 12586242.
Although there are several exceptions, the gist is pretty much as above for GMT800 (other vehicle platforms will make this more confusing).

If you go to GM Parts Giant's VIN DeCoder

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it'll give most of your RPO codes and help you shop for your replacement pcm(s).
Do NOT buy anything from GM Parts Giant! Use it to figure out what to buy, but buy somewhere else.