Hey there! I'm having some trouble with my 2002 GMC Sierra 1500 z71 4x4. It has the 5.3l v8 and 4l60e. Just the other day I was leaving work and the trans started acting up. It would shift fine from 1st-2nd but was hard to shift from 2-3rd,(had to rev it high and feather the gas befor it would shift into 3rd. Needless to say no overdrive and tow hall won't work. Made it most of the way home but then it stalled. Every time I start it it starts and runs fine, but as soon as you put it into rev or drive it stalls right away. Had a code crank position censor. Changed it this morning and ofcourse I had the battery disconnected so it reset comp. Started truck runs fine small misfire and it sounds like it has a small vacuum leak around throtle body area(still can't find?). But same problem truck stalls when gear is ingaged.
Message center flashed (service 4x4 system once or twice when stalled out, and the last time I tried it said check diff fluid?)
Any help or suggestions would b greatly appreciated
Thanks for reading!
Stu

 

check your fluid in your trans on transfercase and rear and front diff

(theres a chance that one can be locking up due to lack of oil)

also it slipping and you having to feather it to get it into third could be a bad clutch pack or once again lack of fluid, also another thing it could be your torque converter going bad

 

also to try to find your vacuum leak take one of the vacuum hoses off and blow smoke into it and smoke will blow out of where the leak is. its very primitive but it works everytime for me

 

Trans fluid is good and nice and red, haven't checked the diff fluids yet. Pretty cold here so I gotta warm up every hour or so.
I read on one of the forms that it could be the torque converter but a friend told me to put the truck in neutral and see if it rolls then try it in drive (obviously with the truck off) and if it rolls then the TC is good, (not locking up). Tried it and it rolls.
Also another friend said they have seen this happen in different cars n trucks and it was the neutral safety on the side of the trans.
I have. Buddy coming by later with a snapon scan tool so hopefully something pops up.
It didn't seem like the trans was slipping the speed keeps up with the revs. It seems more like an electrical, censor or module problem than mechanical.

 

So I bit the bullet and bought a OTC genisys 3.0 this morn. $500 used.
Got a fail since clear code P0706 trans range sensor performance. This transmission is under warranty till April 2012 or 327000km (which she's just at 310000) so hopefully BandN transmission fix it right this time. Not to bad mouth them but I've heard a lot of bad things about them.
Thanks for any help and hopefully I can help someone out sometime!

 

Good thing it's still under warranty!

Also that's a good deal on the Genisys ... Wouldn't mind owning one myself.

 

Just an update for those who may be following or for those who may have the same problem. This morning I decided to try a few thing out while I was waiting for the tow truck. Fist I switched the transfer case into neutral and tried changing gears and the truck kept running. So I put trans in N and trans case in 4lo. Shifted into drive without foot on brake and she rolled! Woohoo I'm getting some where. When I stop tho she stalled. Back in N started fine put into R movement! Only thing I could come up with was torque converter. Sure enough when I brought er to the trans shop tech did same thing I did. First thing he said ur torque converter is locked. Why he didn't know yet. Only 8 months old he said that's when the pre owner had rebuild. My first assumption was they probably put the old one back in as this is a shop that rebuilds them themselves. Good thing is it's under warranty!

NullHead- I found my genisys on a kijiji.com. I'm sure if u look on web sites like that but more for your area, Im pretty sure kijiji is only in Canada but not positive.
He was askin 650 offered him 500 he took it. Need a new bat but as long as u have it plugged in works great. Otherwise it'll die after about 5 min. Came with loads of inserts, pathfinder domestic 2004, USA 2007 domestic and Asian, gas m-p, 2004 abs/airbag, scope with info tech and GM sps reprogramming.

 

Its electrical, a bad neutral safety switch has been known to throw a P0706 code.

 

Ya I scanned it with my genisys the day I got it. Picked an acdelco one up for $60 at my local parts store. Replaced it reconnected the bat. Cleared the codes. Started er up, np. Same stalled when I shifted into gear. Scanned it again got a couple abs codes but they have been there for a while. Also got a VSES code don't remember the#. That was also on befor I changed Trans range sensor(neutral safety switch). I assume VSES is the same thing as VSS or vehicle speed sensor? Figured I was done messing around in -20/25 deg weather. Transmissions under warranty anyways so I just popped on the tow and brought er down to the shop