'04 tranny problem

[chadc77]

Guys,

 

I have a "04 GMC regular cab 4X4. I have a issue with my 1st -2nd shift from a stop @ 3/4-4/4 throatle. The shift firmness is ok for this throatle position but the transmission stumbles when it shifts. Also @ light throatle the 1st -2nd shift is sometimes harsh but does not stumble. I have had the dealer look @ it and he has said he felt the issue but could not give me a answer on what was wrong. They did give me a extended warranty 4 year 60,000 mile in writing. I like the truck but I want this issue resolved. I would be thankful for any helpful info..............

[mcreyaufmiller]

We are talking about a similar issue in another thread, but to put it simply, the 4L60E (more than likly what you have) is a weak tranny, there are a lot of problems, for example pump pressure. this tranny lacks the proper pressure to make the tranny shift correctly all of the time. I believe a shift kit would solve your problems. Go to www.bulkpart.com and do the contact us button, tell them your problem and they will respond quickly about what they have to fix it.

[hihosilverado]

My 04 shifts smooth at all shifts except light throttle 1-2 from a stop.......man it is harsh....but only sometimes. My 02 shifts much firmer in all gears but not harsh and the shifts are consistent.........I have been planning on taking it in but I hate the hassle of it......

[hihosilverado]

I should mention I did take it in once but the dealer said they drove it and did not feel it (possible because it is intermittent, although increasing in frequency now) and that there were no codes stored in the trans.......

[Markeaux]

Guys,

 

I have a "04 GMC regular cab 4X4. I have a issue with my 1st -2nd shift from a stop @ 3/4-4/4 throatle ...

 

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So that is basically a full-throttle shift ... I would not be surprised if the torque management was kicking in ...

[biochemist]

I think the Torque Management is right also, but as I said earlier these transmissions are always learning...mine is also harder shifting at low throttle, but it learns and the next time I do this it is soft again. I tested this a few times today, but also, the weather is cold here and I have the extra tranny cooler...anyway, I remember in the summer trying to get an accurate fluid reading, but it was always barley over warm, never hot to the touch...temp of the fluid will also effect shifting. There is a TSB for harsh 1-2 but it is supposed to set the SES light...you do not have this? I has nothing to do with your tires either I would not think. I guess it is also tough to tell what you mean by harsh...jerks you out of your seat, a slight bump, does it make a sound, or just a bit more noticable than a regualr shift? Anyway, these tranny's are adaptive and try to second guess the driver sometimes by learing your driving habits. The Allison does this also, my brother works for Allison BTW, and when they first came out customers complained about the harshness of the shifts...they actually made a video about it for customers...but soft shifts mean the transmission is slipping (not an instant transition between gears)), which is fine and gives you the soft shifts, hard shifts mean no slipping...allisons, busses, HD trucks (the towing and harsher use require harder shifts, cannot have the transmission slipping for the sake of the ride)...but most customers complain about this, they prefer a car like shift...well that means you get a wierd shift once in a while...it is trying to give you the best of both worlds...some people prefer firm shifts and tune with westers or other aftermarket chip....all depends on you, harder shifting does not harm anything. My cousin has a silverado that is tuned, all shifts are quick and firm...you can make it any way you like...cool ,...let me know if I am correct or any thoughts you may have, I am no expert by any means just have talked alot with experts, later,

[mazingo]

My trucks tranny isnt learning me I think I am learning it. With my diablo prog my tranny shifts firm and quick but sometimes it cant decide if it wants to pull off in 1 or 2 ( mostly from stop lights). Sometimes it does a 2-1-2 shift realy quick people think I am trying to burn out and I really aint.

[chadc77]

My trucks tranny isnt learning me I think I am learning it. With my diablo prog my tranny shifts firm and quick but sometimes it cant decide if it wants to pull off in 1 or 2 ( mostly from stop lights).  Sometimes it does a 2-1-2 shift realy quick people think I am trying to burn out and I really aint.

 

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[chadc77]

Guys, hanks for all the replies,

The light throatle shift is just firmer than normal. It does not jerk your teeth out. The 3/4 - 4/4 throatle 1-2nd shift from a stop is the one I am really worried about, it stumbles bad. I have also noticed @ times if I get on the gas and let up it clunks. I want to keep this truck for a long time and would like to get this resolved. What do you guys mean by torque management?

[jhm]

We are talking about a similar issue in another thread, but to put it simply, the 4L60E (more than likly what you have) is a weak tranny, there are a lot of problems, for example pump pressure.  this tranny lacks the proper pressure to make the tranny shift correctly all of the time.  I believe a shift kit would solve your problems.  Go to www.bulkpart.com and do the contact us button, tell them your problem and they will respond quickly about what they have to fix it.

 

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Why do you think that he has the 4L60E tranny? What years are they used on? I have an '01, not sure what tranny it has. Last year it would not go into od until about 65-70 mph. Dealer replaced a valve, did it from the side, said it was a simple job. Since then no problems.

[hihosilverado]

All 1/2 tonners with an auto since back in the late 80s, or early 90s, use a 4l60E. When mine shifts harsh from 1-2 the whole truck shakes violently. It is quite embarassing when riding with a passenger and they comment. I think it is probably normal, slightly hard shift combined with windup in the driveline due to random factors equals shake.

[Markeaux]

TM:

Torque management is GM's effort to reduce transmission wear by reducing engine output through timing retard during “abusive” maneuvers. The problem here is that GM believe acceleration from a stop is an “abusive” maneuver, as is punching the throttle during a highway merge. Both of these maneuvers cause an immediate reduction in engine power.

 

With the GEN III VS engine, Torque Management is a function of the PCM that reduces engine power under certain conditions, included in which, is the transmission upshifts and downshifts.

 

Torque Management is performed for the following reasons:

 

1. To prevent overstress of the powertrain components.

2. To prevent damage to the vehicle during certain abusive maneuvers.

3. To reduce engine speed when the IAC is out of the normal operating range.

 

The PCM monitors the following sensors and engine parameters to calculate engine output torque;

 

- Air/Fuel ratio

- Mass Air Flow

- Manifold Absolute Pressure

- Intake Air Temperature

- Spark Advance

- Engine Speed

- Engine Coolant Temperature

- A/C Clutch Status

 

The PCM monitors the torque converter status, the transmission gear ratio, and the engine speed in order to determine if torque reduction is required. The PCM retards the spark as appropriate to reduce engine torque output if torque reduction is required. The PCM. also shuts off the fuel to certain injectors to reduce the engine power in the case of an abusive manuvers.

Instances when engine power reduction is likely to be experienced, are:

 

a. During transmission upshifts and downshifts.

b. Heavy acceleration from a standing start

c. The IAC is out of the normal operating range.

d. When the driver is performing stress-inducing (abusive) maneuvers such as shifting into gear at high throttle angles or shifting the transmission from reverse to drive to create, a rocking motion. The driver is unlikely to notice the torque management actions in the first two instances.

 

The engine power output will be moderate at full throttle in the other two cases. The PCM calculates the amount of spark retard necessary to reduce the engine power by the desired amount. For example the PCM disables the fuel injectors for cylinders 1, 4, 6, and 7 in the case of an abusive maneuvers.

[jhm]

I had never heard anything bad about the tranny in the 1/2 ton trucks. I researched a little and the only thing I saw was they are not intended for towing, and if they do end up being rebuilt you will only get 35K out of it. The thing about towing was from a trans repair shop website, the thing about only getting 35K out of a rebuild was from some Camaro website. The other thing I found was torque mgmt is not just a GM issue, Chrysler uses it as well, probably lots more do too. If these trannys are built with weak pumps, etc, GM needs to go back to the drawing board before they get the same tranny reputation as chrysler products!

[biochemist]

I had never heard anything bad about the tranny in the 1/2 ton trucks. I researched a little and the only thing I saw was they are not intended for towing, and if they do end up being rebuilt you will only get 35K out of it. The thing about towing was from a trans repair shop website, the thing about only getting 35K out of a rebuild was from some Camaro website. The other thing I found was torque mgmt is not just a GM issue, Chrysler uses it as well, probably lots more do too. If these trannys are built with weak pumps, etc, GM needs to go back to the drawing board before they get the same tranny reputation as chrysler products!

 

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No Way about the towing issue, I know people who tow all the time, their trucks last forever. Fleet construction trucks (which are not maintained well at all as you amy know) last forever. That website just wants to get your buisiness or install some mods for you (trying to scare you basically) If you think about it these have been around a long time, very few issues. I mean forums like these are typically for people that have questions or sometimes bizzare experience, what about the other ~800 thousand owners out there? All 1/2 tons, tahoes etc...have the 4L60E tranny, even the hummer h2. In that case it is towing its own fat a$$ around, something to think about...later

[biochemist]

All 1/2 tonners with an auto since back in the late 80s, or early 90s, use a 4l60E.  When mine shifts harsh from 1-2 the whole truck shakes violently.  It is quite embarassing when riding with a passenger and they comment.  I think it is probably normal, slightly hard shift combined with windup in the driveline due to random factors equals shake.

 

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hiho...does this usually happen when you are beind someone that makes you take off slowly? Or possibly going down hill slowly? I have noticed a firmer shift in these two circumstances, BUT, the next time the transmission seems to have learned and shifts smoothly again. I think it is just trying to manage your driving style comparing to the recent past...remember these are computer controled and GM cannot please everyone...some like hard shifts, some smooth...depends on the person. SOme poeple who drive these trucks never notice this as they are always taking off at medium to high throttle...if you vary alot like I do...you get a odd shift once in a while...but mine shifts real smooth most all the time ~90+% anyway...I admit when I first noticed this I was like what TF going on, but there is a pattern, only happens under certain circumstances, like the ones I mention above. They are adaptive, how could it shift the same way all the time anyway? The truck weighs ~6000 lbs, coupled with a very long drive-train (and transfer case)...any of this reasonable? Let me know what you ahve found out...later