I'm Getting RPM fluctuation at highway speeds maybe TCC Lock-up?
- Thread starter Mike w
- Start date
What other maintenance was done on the tranny over the years? Was it regular and by the book, or was this the first time it was touched?
If you didn't change it when you got it, assuming you bought it used, this is the cost of that deferred maintenance. 
If you bought it new.....there's nothing I can say. 
If you bought it new.....there's nothing I can say. 
The dealer didn't want to be blamed for the inevitable failure.
But surely there are other competent independent mechanics who will do what the customer asks? Dealers cannot be trusted, it seems, even when they DON'T do a job. If they lie about why they won't do it.
Too bad.
But surely there are other competent independent mechanics who will do what the customer asks? Dealers cannot be trusted, it seems, even when they DON'T do a job. If they lie about why they won't do it.
Too bad.
Take it to a competent independent transmission shop, tell them the whole history, and start saving.
Sometimes, I've read about multiple flushes with new proper fluid can recover functionality. Only a professional who can lay their hands on it can tell for sure. On a forum all we could do is guess.
For the benefit of future readers (not trying to rub it in - I know you feel badly) - THIS is another reason for a competent pre-purchase inspection. WIthout knowing the problems that a previous owner might be trying to fob off on you, you can't have any idea of a fair price to offer to compensate YOU for the risk of ignored maintenance you might be assuming.
Sometimes, I've read about multiple flushes with new proper fluid can recover functionality. Only a professional who can lay their hands on it can tell for sure. On a forum all we could do is guess.
For the benefit of future readers (not trying to rub it in - I know you feel badly) - THIS is another reason for a competent pre-purchase inspection. WIthout knowing the problems that a previous owner might be trying to fob off on you, you can't have any idea of a fair price to offer to compensate YOU for the risk of ignored maintenance you might be assuming.
RayGumm
Member
- Apr 16, 2014
- 630
- Jun 24, 2014
- 287
yes just what you see in the video. it was jerking a bit but after the fluid change the jerking clearedRayGumm said:Wait... how much fluctuation are you talking? After it settles into TC lockup, it doesn't fluctuate more than 75-125 RPM'S. Your video looks normal to me besides the Airbag lite...mine (and every other auto trans vehicle I've driven) does the same...
HARDTRAILZ
Moderator
- Nov 18, 2011
- 49,665
SirRobin53
Member
- Apr 27, 2014
- 118
BlazingTrails
Member
- Apr 27, 2014
- 19,409
gmcman
Member
- Dec 12, 2011
- 4,656
Mike, I don't know your financial situation but this is what I would recommend....worst case, you get it rebuilt.
First of all, a pan drop and filter is about 1/4 of the total fluid capacity. What I would do is get another filter just to have it (deep pan) and check the fluid again...you will want to change the fluid again soon and maybe after the next change to replace the filter again.
Where did you get the filter and/or did you change it yourself?
What is the fluid level?
Did all this happen before the fluid change or after?
I would maybe wait on the flush since you don't know the history...could dislodge too much material clogging the filter.
When mine was at about 165K I had a very noticeable 2-3 flare and what had happened was the check balls pounded the separator plate so much that one actually pounded through, resulting in a pressure loss. This is very normal for these transmissions but when it happens is anyone's guess, depends on driving habits.
It looks as like the TCC is either slipping or the PWM control is erratic...or both. This could be either from debris or from a pressure loss.
What is your mechanical ability? When I removed my valve body the first time it gave me sweaty palms but wasn't bad at all, intimidating at first mainly because it is my daily driver but if you're organized it's not bad.
Before you take it in, lets see if we can figure it out.
First of all, a pan drop and filter is about 1/4 of the total fluid capacity. What I would do is get another filter just to have it (deep pan) and check the fluid again...you will want to change the fluid again soon and maybe after the next change to replace the filter again.
Where did you get the filter and/or did you change it yourself?
What is the fluid level?
Did all this happen before the fluid change or after?
I would maybe wait on the flush since you don't know the history...could dislodge too much material clogging the filter.
When mine was at about 165K I had a very noticeable 2-3 flare and what had happened was the check balls pounded the separator plate so much that one actually pounded through, resulting in a pressure loss. This is very normal for these transmissions but when it happens is anyone's guess, depends on driving habits.
It looks as like the TCC is either slipping or the PWM control is erratic...or both. This could be either from debris or from a pressure loss.
What is your mechanical ability? When I removed my valve body the first time it gave me sweaty palms but wasn't bad at all, intimidating at first mainly because it is my daily driver but if you're organized it's not bad.
Before you take it in, lets see if we can figure it out.
gmcman
Member
- Dec 12, 2011
- 4,656
Sorry, I see that it was doing this prior.
Take it out again and put the shifter in 3rd, the TC should still lock and see if it still fluctuates.
Is it me or is this a normal lockup with the 3.42 or 3.73 ratio? I have the 4.10 so I can't say but it seems abrupt for a factory PWM control. Just something that made me think it could have previously had a PWM eliminator installed albeit incorrectly. I doubt it but it was just a thought.
Take it out again and put the shifter in 3rd, the TC should still lock and see if it still fluctuates.
Is it me or is this a normal lockup with the 3.42 or 3.73 ratio? I have the 4.10 so I can't say but it seems abrupt for a factory PWM control. Just something that made me think it could have previously had a PWM eliminator installed albeit incorrectly. I doubt it but it was just a thought.
gmcman
Member
- Dec 12, 2011
- 4,656
In your case it will be a crap shoot since we don't know the condition of the clutches. However the vette servo and the Sonam super hold can be swapped later if needed.
What I would recommend is to get the Transgo TCC PWM eliminator valve and the vette servo. I personally don't like to go with a shift kit since it's more work to undo. ..even though most people leave them in.
I would also get a new separator plate from the dealer, I strongly recommend this against aftermarket....unless you contact Transgo.
Also get the Torlon check balls.
Torlon balls, vette servo, PWM eliminator, I would get from Pro Built Automatics.
New plate, from the dealer.
I would start here and should fix your issues, and extend the life of the trans if you don't have burned clutches.
Much cheaper than the alternative right now.
What I would recommend is to get the Transgo TCC PWM eliminator valve and the vette servo. I personally don't like to go with a shift kit since it's more work to undo. ..even though most people leave them in.
I would also get a new separator plate from the dealer, I strongly recommend this against aftermarket....unless you contact Transgo.
Also get the Torlon check balls.
Torlon balls, vette servo, PWM eliminator, I would get from Pro Built Automatics.
New plate, from the dealer.
I would start here and should fix your issues, and extend the life of the trans if you don't have burned clutches.
Much cheaper than the alternative right now.
gmcman
Member
- Dec 12, 2011
- 4,656
This is when I replaced my PWM valve.
http://gmtnation.com/forums/topic/7238-removed-pwm-control-from-tcc/?hl=%2Bpwm+%2Bcontrol
http://gmtnation.com/forums/topic/7238-removed-pwm-control-from-tcc/?hl=%2Bpwm+%2Bcontrol
- Jun 24, 2014
- 287
Well I'm going to install a rebuilt transmission and have the original rebuilt The cause of my problem was water intrusion the truck is jerking pretty bad at 60mph TC is shuddering too. found proof of the maintenance records which WERE up to date so no deferred maint. Do i need to do a relearn when installing a different trans? Any information/tips would be appreciated on the removal...
BlazingTrails
Member
- Apr 27, 2014
- 19,409
The trans is easy to remove with about 18" of extensions for the top 2 bolts. Install an aftermarket trans cooler, that is most likely where the water came from. I would reset the pcm. I would also install a corvette servo. $20 on eBay and 10 min to put in. 
- Jun 24, 2014
- 287
Thanks which aftermarket cooler? the trans i'm purchasing has trans go shift kit all new clutches new TC Heavy duty sunshell and sonnax sure hold. I will have the other one rebuilt or sell it as a core.BlazingTrails said:The trans is easy to remove with about 18" of extensions for the top 2 bolts. Install an aftermarket trans cooler, that is most likely where the water came from. I would reset the pcm. I would also install a corvette servo. $20 on eBay and 10 min to put in.
BlazingTrails
Member
- Apr 27, 2014
- 19,409
gmcman
Member
- Dec 12, 2011
- 4,656
Something to consider, and I know I will likely do this when I ever replace my trans...is to look into an Edge converter. If you plan on keeping it for awhile then at least contact them directly. There is a science in regards to torque converters and these converters, while pricey, are very well thought out and AFAIK, they may even offer a slight increase in city mileage.
I would contact them for sure and at least get the scoop, has been a couple years since I did and the info may have changed.
I would contact them for sure and at least get the scoop, has been a couple years since I did and the info may have changed.
gmcman
Member
- Dec 12, 2011
- 4,656
I would also find out what has been done in regards to a "shift kit" first before installing the vette servo. The Sonnax super hold which sounds like is already installed will increase the shift firmness where the vette servo would if the Sonnax wasn't there. Not to the same firmness but they work in conjunction...somewhat.