NutNbutGMC, Son of a gun, mark45678 & ALL others-Late shift into 1st

[Billy14]

First of all,

Thanks to all for convincing me to get the single drive shaft. So smooth, so tight, so much more responsive. After supplying my dealer with numerous print-outs off of this site, they did an absolutely wonderful job. Used a die grinder to cut the welds, ground smooth, and re-painted the cross member. Can hardly tell the truck didn't come this way from the factory. smile.gif

Late shift into 1st :mad:

If you don't remember, this was a problem I encountered while easing the truck to a complete stop on grade holding only with the throttle, no brake applied. It wouldn't shift into 1st until about 1500 RPM was achieved, slamming down finally breaking both tires loose with a wrenching jolt. :eek:

The dealer & bulletin I have sited in the past from GM blamed it on the oversize tires (BFG 295's). When I tried the same senario with a friends' new, completely stock HD identical to mine, it did the exact same thing with my dealer's Service Manager in the passenger seat. He pulled two trucks off the lot & found the same results prompting him to get some info from GM direct.

GUESS WHAT? It worked. smile.gif

When they replaced my driveshaft they also reprogrammed the TCM. Now, I can approach a steep grade in 2nd, let the truck come to a complete stop using only the throttle, (NO BRAKE) & between 2 - 4 mph that big ole Allison drops into 1st like a transmission should. :D
With the new driveshaft and this mod, the truck runs soooo smooth through all the gears, I really can't describe the difference. ;)

Here's what my service invoice states:
Cust states trans jerks into 1st on enclines when accelorating
TCM Misprogrammed
Reprogrammed TCM with updaded program
K5364 0.7

This should help a bunch of you guys & thanks for your input to me,

Billy

[mark45678]

COOL glad to hear your problem was solved!!!!! I will check in with my GMC buddy and see if this is the up date he did for me? Happy trails!

[Billy14]

Mark,

This update supposedly was released this past Monday. Don't know for sure if it originated from my problem & dealer or not.

Billy

[NutNbutGMC]

^,,, Another satisfied forum member. Glad your machine is at 100% again.

[SteveO]

Billy14,

Yes, your correct, the TCM update was released Monday.. The Part # for this on a 2001 is 15175857 Description of update
"new calibration to accomodate overdrive defeat switch and address 2-1 shift quality"..

Believe me your not the one who caused GM to release the update.. This one has been in the works for a long time......

GM issued a bulletin about two months ago advising the dealerships on what was going on when you hold the truck using the converter instead of the brake pedal..

[ 03-27-2002: Message edited by: SteveO ]</p>

[7mmSTW]

This reprogram takes care of the feeling like someone rearended you at a light while rolling to a stop? And the "neutral drop" at takeoff from the light? It's about time for that, ours has been doing that constantly and all the dealer can say is that it is trying to learn to adapt to the driver. If that is the case ours has ADD. I guess it takes more than 7,500 miles. :rolleyes:

Later

Seven

[OldCarKook]

Boy I gotta tell you, of all the forums that I have participated in, this one blows them away for factual concise information. You guys have it nailed and I'd like to thank you.

I pick up my new 2500HD CC shortie tomorrow AM and will be listing ALL of these items on the first service appointment.

Many many thanks to all here, especially NutnbutGMC, who is committed to the right brand!

[NutNbutGMC]

;) smile.gif

[Billy14]

SteveO,

Many thanks to you & all. smile.gif I really don't care if I can make claim to this TCM update. It just really pleases me, :D & I'm sure most all participating in this forum, that GM finally addressed this problem (what I would consider to be a critical issue).

I have to say, I was hell bent in high water not to let them get away with blaming this problem on my 295 series tires.

Thanks again & I sincerely hope my input has helped others.

Billy

[BigAl]

"Rumor" has it Trussman is scheduled to get the new calibration here soon as well. Be on the lookout for a post (Buckman?) on how that turns out since it appears Trussman has gone over to "The Dark Side". tongue.gif

[Buckman]

BigAl

Since Trussman's trip to the dark side, it's a bit more difficult to stay in touch. If I hear anything, I'll let you know. "MAY THE FORCE BE WITH YOU"!!!! :D

I'm sure that we would all like to hear that the calibration helped him out. Now, where did I leave my light saber???? :confused:

[Jimamatic]

7mmSTW,
What you're talking about with this calibration program sounds exactly like what I need. My truck
has a bump just as I come to a stop. Then when I
launch, it has a slight slip. Bugs the s*** out of me. Have'nt tried the converter thing on a hill yet. I'll try it today. The wierd thing is this will only happen after the tranny has totally
warmed up. When cold the whole drive train is
smooth and tight, (two piece d/s). Sound like
this new TCM update might help. Any ideas?

[BigAl]

Jimamatic,

Hate to bust your bubble, but I'm bettin' what you are encountering is the result of the 2-piece driveshaft and NOT the tranny. I drove one for a week one time and I would have sworn the tranny was shifting funky (and I'm supposed to know the difference :( ). Turned out it was the 2-piece drive shaft wrapping and un-wrapping. Quickest way to tell.........the tranny seems to do it's thing somewhat randomly. The 2-piece driveshaft seems to do it EVERY stop and start.

The 2-piece driveline phenomenon manifests itself as a very slight "bump" when coming to a stop, and a very slight "slip" sensation when taking off again. Try this.........come to a full stop from about 30 - 40 MPH real hard (like everything you can do short of slipping the rear end!). Most of the time, this will produce the most pronounced "bumps" and "slips". The tranny wouldn't care how hard you stopped........the driveline does, cause it magnifies the wrap-up!

Let us know! smile.gif

[sonofagun]

Billy14,

Glad you get a smilie face out of the effort.

Enjoy.

Bob

[Jimamatic]

Thanks BigAl.. I'll try that and let you know.
I just got back from driving around and tried
stopping on a hill and held it with the converter.
Did'nt touch the brakes. Not a problem. I don't
think it's a 2-1 shift problem. Once I get past
the slip on launch, it glides through the gears
like a hot knife through butter. I'll just bet
you're right on the money with the two piece.
What you described is exactly what my truck is
doing. Wierd it only happens when it's warmed up.
After it is warm and it starts doing it, it will
keep doing it consistantly.
I've got a K25743 truck which I'm 99.99% sure is
covered by TSB #01-04-17-001A for launch shudder.
I had my truck in a while back for mild shudder
unloaded. The service writter told me that TSB
did not cover my truck. I then produced the acual
TSB which I had down loaded and showed him otherwise. He didn't know what to say. That's as far as I've pushed it to date, but it looks like I could be in for quite a battle. Just want to
be armed to the tooth with info before I make
another appointment. Thanks again for all the
help out there guys and gals. This forum is awesome....

[mattb5150]

I notice this new TSB mentions 2001's but does it apply to 2002's also.

Matt B.

[Billy14]

mattb5150

Yes,mine is a 2002.

Billy

[Buckman]

BigAl,
UPDATE on Trussman. I hear that Trussman got the new calibration programmed in his truck and "Big Improvement". Now; if we could just get him back from "The Dark Side". By the way; I found my light saber. It was in the last place I looked!!! smile.gif :D

[Derek M]

I believe this is the same problems discussed in:

http://forum.62-65-dieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=003197

http://forum.62-65-dieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=003234

I had my truck in yesterday. The dealer paperwork said they updated the PCM, hehehe. Did they mean TCM, or did they actually update the PCM which would basically mean they updated the wrong computer. I don't believe they addressed the correct computer. Nor it's my belief that the PCM or TCM is responsible for the bump/slack/clunk condition we speak of. I'm gonna give them the benefit of the doubt and try to service it again along with dropping subtle hints as to what the problem is. I'm gonna call my SA back and see if I can find the details of what exactly was updated on the PCM yesterday.

[Buckman]

Derek M :

The calibration update I mentioned on the previous post was to address various problems such as harsh 2-1 downshifts, delayed 2-1 downshifts and shift busyness when in cruise and/or loaded, amongst others. My understanding is that to realize the full benefit of the calibration update requires that the TCM (transmission control module) and the PCM (power control module) both be updated on the 2002 truck. As far as the bump/slack/clunk condition, I believe that BigAl's advice regarding the driveline is likely more on target for your concern. Hope your dealer gets it resolved soon.