1994 GMC 4l60e transmission shifting problems

lostsoul
40

Asked by lostsoul Jan 17, 2011 at 07:46 PM about the 1994 GMC Sierra 1500 C1500 SLT Extended Cab LB

Question type: Maintenance & Repair

I've got a 1994 GMC Sierra 4X4 5.7 I purchased from an older couple. It has been sitting a year. She said years ago they had tranny trouble; it would stay in low. She took it to a shop where she said they cleaned a switch and reset the computer.
After that it worked fine for a long time, then would intermittently have the same problem, then be fine. I got the truck and it wouldn't shift out of low.I pulled the pan, which was real clean, just a very light coating of gray. I changed the 2-3 solinoid, new fluid and filter.  I also noticed the speedometer wasn't working.  I then changed the speed pickup on the transfer case, which did not help the speedometer.
Now the truck will shift 1-2 manually, but when you put it in drive, it free wheels: nothing at all; no drag or anything.  The computer just checks code 12.  If you put it in drive, it stays in low.  If you put it in low and lift the handle, it will go into second immediately and when you move to drive---nothing.
Will a bad computer do this? there is no governor or TV cable on this tranny....any ideas?
Today I must have gotten my 20 minutes on the computer, because I got error code 16, which is vehicle speed buffer....!  I need to know where it is....don't even know what it looks like!
Thanks---Stuck in the 70's

5 Answers

witty
170

it'sbehind the glove box. open the box,and take out the black liner with 4-7mm bolts. look for a white square flat box with 2plugs going into it. thats ur vsb. make note of the numbers on it, they make many different ones!

17 out of 17 people think this is helpful.
lostsoul
40

Where can I find one? Dealer in town can't get one! Have any on-line ideas?

4 out of 4 people think this is helpful.
Robert Clark
95

sounds to me that it is the computer going cuz i replaced mine twice already and there not cheap!!!! but its worth it now cuz since i put this second one in ive never had a problem with it!!!

3 out of 3 people think this is helpful.
jmonroe92
120

my tuck is doing the same thing and ur saying its not the shift sencer or anything cuz i also changed the one on the transfer case witch done nothing for me what did u really have to do to fix the problem??

12 out of 12 people think this is helpful.
Reggie Gardner
50

am having problems after 71/2 years n i have 250,000 miles its sayn P0753-P0758 shift solenoid ssb n P1864 nodef n P1886 nodef , can sum one tell me what i need to do , its still running n shitn out n am driven it but seam like sumthing is holdn it back !!! can sum one tell me what i need to fix to get it straight ????

5 out of 5 people think this is helpful.

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