1994 GMC 4l60e transmission shifting problems

lostsoul
40

Asked by 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

23 Answers

witty
340

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!

34 out of 34 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
125

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!!!

6 out of 6 people think this is helpful.
jmonroe92
190

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??

19 out of 19 people think this is helpful.
Nick_machanic
160

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

11 out of 11 people think this is helpful.
Nick_machanic
160

Any questions or need of repair please call 513 808 5967

5 out of 5 people think this is helpful.
crash47
70

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

7 out of 7 people think this is helpful.
Frederick Heims Jr.
60

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

6 out of 6 people think this is helpful.
Tooloose
425

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.

2 out of 2 people think this is helpful.
Reggie Gardner
150

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 ????

15 out of 15 people think this is helpful.
Dwreck Slimms
20

Did youver get it fixed?

2 out of 2 people think this is helpful.
Jody1979
610

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

26 out of 26 people think this is helpful.
Jody1979
610

Do I have to reset computer

22 out of 22 people think this is helpful.
Jody1979
610

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

9 out of 9 people think this is helpful.
ARABengineer
55

check fluid level .

2 out of 2 people think this is helpful.
Jody1979
610

I bought a new computer and rebuilt tranny still no drive

4 out of 4 people think this is helpful.
Michael Hummell
40

can my trans make engine to lose power when gets hot?

4 out of 4 people think this is helpful.
bradyp1999
300

my 94 gmc 1500 is acting likr this also. its an automatic , but when i put it in drive it will not shift out of 2nd, even when i shift from first to second manually it will go from first to second gear fine, then i put it in drive or overdrive and it will not shift again. also my speed odometer is acting really funny, its flying back and forth , definately think its an electric problem

30 out of 30 people think this is helpful.
Defeojack1
40

Yes that's has happen to two of my 93 Chevy Silverado 4x4 , 1 and 2 fine then free wheel in overdrive. Just change 1-2 - 3-4 solenoids first and if that doesn't work change the computer per Ebay it's the cheapest. Hope this helps JJD

4 out of 4 people think this is helpful.
metalbychris
50

My buddy changed his distributor and cured the tranny problems.

5 out of 5 people think this is helpful.
Hotrod333
100

I had the same problem I couldn't shift out of second and when I could my overdrive was not working so I would burn through the gas i and couldn't figure it out. But I finally looked at where the wiring went into the Trans and found out the 4x4 linkage was to close to the wiring so every time I locked 4x4 in it would hit the wiring and push the plug in the transmission causing it to leak. You have to clean out the plug going into your Trans I used wd-40, probably not the best thing but that's all I saw and then blow some air into it and lwt it dry unplug the battery for 30 mins and worked just fine. I don't not know why that 4x4 linkage is so close to the wiring ont the trans though. Oh yeah I have a 97 gmc k2500 350 4l80e

2 out of 2 people think this is helpful.
hollidizay
0

i was having problems as my trans would not shift unless i shifted manually so i changed output sensor and nothing changed so after reading hotrod333s post i also disconnected my battery for 30 min and it is all good..thanks!

Chasitylori
0

We have the same issue with our 93 gmc sierra 1500 4x2. Wont shift into second until we let off the gas then itll shift but then theres no over drive. Ive changed the solenoids, fluid and filter and even added lucas antislip. Nothing as worked. Any suggestions. Shop says it needs to be rebuilt. I dont have $1500 to have it done and its my husbands work truck. He needs it fixed asap. Im tired of driving him around. Thanks

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