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

15 Answers

witty
230

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!

23 out of 23 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
105

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!!!

4 out of 4 people think this is helpful.
jmonroe92
150

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??

15 out of 15 people think this is helpful.
Nick_machanic
50

I have a 94 Chevy Silverado 5.7 2wd 4L60e transmission. I had no head lights speed odometer quit working an trans would quit shifting out of 1st gear my diagnosis was to replace solenoid s A/b 1\2 2/3. An the TCC solenoid the signals from the power control model tells it when to shift check the Orange an yellow wire on the harness that connects to your driver side fire wall. 12volts to transmission to carry proper current

4 out of 4 people think this is helpful.
You think this is helpful.
Nick_machanic
50

Any questions or need of repair please call 513 808 5967

1 out of 1 people think this is helpful.
crash47
20

I have a 94 Chevy Silverado just used trany in it and it won't shift out makes noise going up hill

2 out of 2 people think this is helpful.
Frederick Heims Jr.
0

I had a similar problem a few weeks ago. Speedometer stopped working and my truck stopped shifting. I changed the speedometer censor located at the on the tail end of the transmission on the driver side. I purchased it at O'Reilly for $34

Tooloose
335

If you have a trans code reader and it codes 72 have a dealer check for bad selector switch. Regular code readers like a snap-on mt-2500 can read transmission data, as where other odb2 readers will not. Specialized tools are required to accurately diagnose trans problems! Leave this to the professional trans shops or GM Trained Professionals, it will get fixed faster, and cost less in the long run. Time is money, don't waste either guessing. 40 + year veteran in automotive repair.

Reggie Gardner
90

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 ????

9 out of 9 people think this is helpful.
Dwreck Slimms
0

Did youver get it fixed?

Jody1979
0

I have a 94 Chevy 1500 just put a tranny in and 1 and 2 nd work good but nothing in drive

Jody1979
0

Do I have to reset computer

Jody1979
0

Somebody help please it's my 3 tranny and all same issues no drive

ARABengineer
5

check fluid level .

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