transmission question

txg · September 28, 2002

on my 1500hd when i accelerate at a fairly quick rate, 3/4 throttle, I can sometimes feel a quick shake as the transmission upshifts. Under normal acceleration everything seems ok.

Anybody have any ideas on what this could be

thanks

asepgrad98 · September 28, 2002

My 02 had the exact opposite problem. It only shuddered under light acceleration. The dealer rewired the alternator and it went away

Unplug the small wires from the back of the alternator and test drive it. If the problem goes away them the rewire job will fix it.

Import Hater · September 30, 2002

Would you say that you had the shudder when everything was warmed up and it was 10-25% throttle on the 1-2 upshift? I know there's TSB 02-04-17-001A for an acceleration shudder, but it invovles replacement of the driveshaft...which I have my doubts in.

Is this rewire the new standard for repairing the problem?

Rob

asepgrad98 · October 1, 2002

Rob,

the accel shudder and the 1-2 upshift shudder are independent. here is some of the TSB.

Transmission 1-2 Shift Shudder, Vibration, Slips, Chuggle (Install Generator Voltage Sense Circuit) #02-07-30-030

Transmission 1-2 Shift Shudder, Vibration, Slips, Chuggle (Install Generator Voltage Sense Circuit)

2001-2003 Chevrolet Silverado

2001-2003 GMC Sierra

with 4L60-E Automatic Transmission (RPO M30)

Condition

Some customers may comment that the transmission slips, a shudder, chuggle, or vibration is felt when the transmission shifts from first to second gear.

Cause

A 12 Hz electrical feedback from the charging circuit may be affecting the transmission pressure control solenoid, causing a fluctuation of the line pressure within the transmission.

Diagnostic Tip

Road test the vehicle under the following conditions:

Throttle position is less than 15 percent.

Engine coolant and transmission fluid are at full operating temperature.

The outside ambient temperature is warmer than 24°C (75°F).

If the condition is present, disconnect the generator 4 cavity connector (2 wires in the connector) and retest.

If the condition is no longer present, perform the correction listed below.

If the condition remains unchanged, the condition will not be corrected with this procedure. Look for other causes of the condition.

Correction

Import Hater · October 1, 2002

Thanks! I thought that the TSB I had didn't quite seem like the right one. That one has the symptoms descried perfectly.

Wow, I wonder how long it took the engineers to figure out that electrical gremlin...

Rob

Texas Z · October 10, 2002

I took my truck in to be serviced on Tuesday because it shuddered between the shifts (like mentioned above) and they couldn't find anything wrong with it. They said they could not duplicate my complaint during their road test and no error codes where found on the computer. I guess they think if the computer says no error codes then all is good (d##n computers). Anyways ya'll mentioned a TSB #02-07-30-030 that addresses this problem, where do you find TSBs and who comes up with them? Do the GM service departments get them or have access to them? I plan on bringing my truck back next week so I want to bring the TSB to their attention.

Thanks

asepgrad98 · October 11, 2002

The TSB's are available to the dealers. They are written by GM and placed on service.gm.com. When i had the shift shudder problem i printed a copy of it and left it on the seat. The dealer took my word for it. Its only like 0.7 hours and a couple dollars in parts. Print a copy of this thread and give it to them. If they dont trust you then there is no way i would ever let them work on the truck after warranty runs out.

sesmith3aa · October 14, 2002

I have a question... If the TSB's are only available to the dealer how were you able to "print a copy to leave on the seat"? Thanks.

MarkD · October 14, 2002

Good Question!!!! (wink, wink)

Connections! (Like GM-Trucks.com :thumb: )

Import Hater · October 14, 2002

The TSB's are available to the dealers. They are written by GM and placed on service.gm.com. When i had the shift shudder problem i printed a copy of it and left it on the seat. The dealer took my word for it. Its only like 0.7 hours and a couple dollars in parts. Print a copy of this thread and give it to them. If they dont trust you then there is no way i would ever let them work on the truck after warranty runs out.

Being a mechanic, of course I won't let them work on it after the warranty. I'm not even sure if I want to let them work on it in the warranty.

I brought my truck in, and I told them exactly the symptoms that is in the TSB and even gave them the TSB number. When I picked it up at the end of the day, I had to figure out myself that nothing had been repaired because parts were ordered.

It's been two weeks, and nobody has contacted me saying the parts are in yet. Pitiful... But I expect no more from Chevy service. I'm half tempted just to buy the parts over the counter and do the TSB myself.

Rob

asepgrad98 · October 15, 2002

Import hater,

They (dealer) wouldnt call me back either. A random guy went to the same dealer as me and got his truck fixed for the same problem while i was still waiting! He saw my thead (on a different site) and called me and told me all about it. I made an appointment and took it in shortly after that.