1-2 shift shutter

[NOSInjected00GT]

hi

first i need to know how i can tell what tranny my 2001 sierra has.. its got a 4.8 in it. thats all i really know. the problem is SOMETIMES under light acceleration )under 2000 rpm) the truck will shift to second nice and smooth and other times it will shift very hard. feels like a shutter almost. but only at times. im hoping its something simple like a pcm programming issue that needs to be updated... anyhelp would be great! thanks!

[drumset5994]

Happened on mine too...it seems to slam it into second only if you say, let off the gas right before it gets set to shift, or sort of "waver" the gas until it shifts to second (for example, when slowly driving beind a plow truck, etc)

 

Thats how it happened on mine...right before it was going to shift to second, i had to slow off the gas because i was following a truck...when i went to pass, it slammed into second pretty hard.

 

I read about it a while back...all i really remember from my readings is that its normal-LOL... and that's all i remember...it hasnt done it for a while anyway so i just live with it.

[GM-Tech]

im hoping its something simple like a pcm programming issue that needs to be updated

 

Could be, though it seems unlikely. Give me your full VIN and I'll see what updates are available.

[turbodarryl]

Hello Guys, My 2001 Sierra has the same problems as the two pre post. Can you check my vin also for updates and service records. 2GTEC19T411252694

[GM-Tech]

Hello Guys, My 2001 Sierra has the same problems as the two pre post. Can you check my vin also for updates and service records. 2GTEC19T411252694

 

<{POST_SNAPBACK}>

 

 

 

 

I don't see any updates for the transmission on this VIN.

[turbodarryl]

I found a GM Technical Service Bulletin # 02-07-30-030A , It on the transmission 1-2 shift shudder, vibration, slips, chuggle ( Install Generator Voltage Sense Circuit )

[Larry]

Had the same problem with a 2002 Tahoe Z71 starting at 20K miles. The dealer did the 02-07-30-030A Bulletin…no change, miraculously found and replaced a supposed stuck shift piston…no change. Changed intire transmission and torque converter for a serta unit….no change. Reflashed the PCM with the latest and gratest…no change. Traded in the Pewter 2002 Tahoe Z71 for a 2004 Silver Birch Tahoe Z71 cured the problem.

 

I have not seen bulletin 02-07-30-030A fix a single 2001 or 2002 4L60E yet. It still bewilders me how that bulletin even made it to print.

 

The boys in the Phoenix Center publishing these bulletins are on crack.