Tranny Issues: Hard Shifting 1-2 and 2-3

[snkp360]

I found this forum after Google'ing and decided to post up my issue to see if anybody had experienced the same thing....

Car
2003 Yukon Denali
139k Miles

Issue
About 2 weeks ago I was driving home from Tahoe and was getting back into town on to surface roads. My car seemed to be driving just fine and shifting normally on the freeway. I stopped at a stoplight after a 3 hrs nonstop drive then accelerated again.

I noticed the shift between 1st and 2nd gear very abrupt and rough, akin to dropping the clutch on a manual, then the shift from 2nd to 3rd was still rough but not as bad. I took note of this to check it out tomorrow.

The next morning and the rest of the week my car drove just fine with no sign of weird shifting.

This past weekend I took a long car trip and the issue presented itself again only after a long period of driving, I noticed it when I went to stop for gas. I had the same symptoms and received a solid check engine light as well. This morning my car seems to be driving/shifting fine again but the check engine light is still on.

I have not noticed any issues just driving around town at all, it only seems to happen when I drive for an extended period of time.


Does anybody have any insight? I found another thread here with someone experiencing similar issues(http://www.tahoeyukonforum.com/forum/showthread.php?t=14012) but it was on a '99 Yukon SLT, that suggested I need a rebuild of my Torque Control Converter.

I am gravely scared of going down the road of a whole new tranny....

 

[scottg918514]

If ur r lucky, just the shift servo going south. Id get the vette shift servo from Oregon performance (eBay) $20 and if u aren't the DIY type tranny shop will install for about $40. Relatively cheap fix if it is the problem. I just got one, but Im putting it on the shelf till I need it.

If u are the DIY, a link to an install write-up: http://www.gmfullsize.com/forum/showthread.php?t=98029&highlight=servo

 

[Jay]

What is your transmission temp when it does this?

Get autozone to pull the code. If it's a P1870 then it's probably the PWM valve for the torque converter clutch. I would wager, however, that at your mileage either an accumulator piston has cracked or that one of the check balls behind the valvebody plate is about to rupture through (may have already done so).

Either scenario means there is a large amount of fluid loss from a circuit and that the PCM is increasing the force motor current to compensate (which will give rough part throttle shifts).

 

[snkp360]

What is your transmission temp when it does this?

Get autozone to pull the code. If it's a P1870 then it's probably the PWM valve for the torque converter clutch. I would wager, however, that at your mileage either an accumulator piston has cracked or that one of the check balls behind the valvebody plate is about to rupture through (may have already done so).

Either scenario means there is a large amount of fluid loss from a circuit and that the PCM is increasing the force motor current to compensate (which will give rough part throttle shifts).

Will Autozone pull the code for free?

 

[Jay]

Every one I've used will. They usually only have one scanner per store and sometimes stores will lend them out to another store so you just have to call and see if they have one before you go.

 

[snkp360]

Every one I've used will. They usually only have one scanner per store and sometimes stores will lend them out to another store so you just have to call and see if they have one before you go.

Cool Thanks.

Oh and I haven't noticed my tranny temp when this happens

 

[2003LS]

outcome

I found this forum after Google'ing and decided to post up my issue to see if anybody had experienced the same thing....

Car
2003 Yukon Denali
139k Miles

Issue
About 2 weeks ago I was driving home from Tahoe and was getting back into town on to surface roads. My car seemed to be driving just fine and shifting normally on the freeway. I stopped at a stoplight after a 3 hrs nonstop drive then accelerated again.

I noticed the shift between 1st and 2nd gear very abrupt and rough, akin to dropping the clutch on a manual, then the shift from 2nd to 3rd was still rough but not as bad. I took note of this to check it out tomorrow.

The next morning and the rest of the week my car drove just fine with no sign of weird shifting.

This past weekend I took a long car trip and the issue presented itself again only after a long period of driving, I noticed it when I went to stop for gas. I had the same symptoms and received a solid check engine light as well. This morning my car seems to be driving/shifting fine again but the check engine light is still on.

I have not noticed any issues just driving around town at all, it only seems to happen when I drive for an extended period of time.


Does anybody have any insight? I found another thread here with someone experiencing similar issues(http://www.tahoeyukonforum.com/forum/showthread.php?t=14012) but it was on a '99 Yukon SLT, that suggested I need a rebuild of my Torque Control Converter.

I am gravely scared of going down the road of a whole new tranny....

snkp360
i'm new to the forum, i'm having the same problem did you ever figure out what was wrong with your tranny?
thanks

 

[showtime1k]

im also getting the p1870 code, i assume the best fix for this is replacing the valve control body?

 

[FLO-LOP 805]

After reading this! issue is mostly when warm or it has been running for a while,fluid gets thinner so it passes quicker thru the valves,not the servo or accumulators,that would be at all times!! Time for a new VALVE BODY!!!

 

[showtime1k]

After reading this! issue is mostly when warm or it has been running for a while,fluid gets thinner so it passes quicker thru the valves,not the servo or accumulators,that would be at all times!! Time for a new VALVE BODY!!!

sounds like my problem, good answer. mines jerks between 1-2 and slips in third after a steady drive on the highway for about 1/2 hr. been in the tranny shop three times and they jus keep changing the torque converter. im going to show them that bulletin and tell them change the valve body. do i need to specify a revised valve body?

---------- Post added at 11:02 AM ---------- Previous post was at 10:54 AM ----------

anyone have a part number for this valve body for 2002 denali or where to find part number