1996 GMC 1500 Transmission problem

kccu · April 23, 2004

Hi, I have a 96 GMC 1500 pickup with a 5.0 v8 and a 4L60E automatic overdrive trans. It will shift from park to reverse fine and from park to 1st fine but will not shift into second until you hit about 30mph and a fairly high rpm. I can't get it to shift on up into third even at 60 or so mph. It acts like a govenor problem but I don't think this tranny has a govenor. Does anyone have any ideas or suggestions on this problem? Could it be an electrical problem with the transmission. No check engine light is on and no cvodes are tripped. Any help would be appreciated. Thanks!

Bluesman123 · April 24, 2004

As you probably already know, the 4L60E is the older 700R4 but with all the shifting done by your VCM. Shift points are determined by the speed sensor input and this is what sounds like is having problems. Depending on your scanner, there may be transmission codes being generated that you can't see.

Before you start throwing parts (which will get really expensive really quick) I suggest you try a couple of things:

1. Remove and clean the connector from the VCM to the tranny. This is back by the tailshaft where it is seriously in the dirt. You can buy a can of contact cleaner from someplace like Radioshack.

2. If that doesn't help, I would have it scanned and diagnosed by someone who can read the full set of codes. This should be about 1/2 hour labor, and I would be inclined to take it to your local GM dealer for this. GM is _supposed_ to give places like Aamco access to all their codes, but you never know.

Good luck,

Dave

kccu · April 25, 2004

Thanks Dave, I will probably do just as you suggest. My scanner is not capable of reading all the codes and I am suspicious of the throttle position sensor or vcm as you suggested. I have an appointment with my friendly GM dealer the first of the week for a checkout.

Kccu