Question for you guys...I have 2007 Chevrolet Silverado 4x4 VortecMax. Sometimes if i slow down really fast or suddenly come to a stop my speedometer goes to zero. Then when i take off again my truck goes and my rpms go up but my truck wont shift and my speedometer doesnt move. Does anybody know what might cause this or have any of you had this problem?

Thanks

 

I think your speedometer is a seperate issue from the tranny not shifting. I've had issues with my 04 GMC instrument cluster, speedometer not working right and temp gauge not working, had it replaced twice. The instrument cluster on GM trucks and SUVs has been a issue. As for the tranny shifting problem. When does it start shifting correctly? If you make a normal stop when you take off does it shift thru all the gears OK? Like 1 to 2 at about 15 to 20 mph, 2 to 3 about 25 to 30 mph and 3 to 4 about 40 to 45mph. I had mine not downshift to 1st and when I take off it stayed in 2nd. I used Lucas automatic transmission additive on my next tranny fluid change and it seems to have cleared up.

 

Thanks for the input bud. It does shift fine when it does shift. The reason I think it's my computer is because if it doesn’t shift out of first, I just put it in neutral and back into drive and then it works fine. It's like I restart my computer or the instrument cluster. Not sure, I've never heard of that.