I have a 1996 gmc jimmy with aprox 150000 miles on it. I noticed it wasn't shifting into overdrive and the rpms were not dropping to where they usually do after OD kicks in and the check engine light came on throwing a p1870 code. My mechanic changed the trans filter cleared the code and sent me on my way.....still no overdrive. He suggested maybe a speed sensor......I would prefer not to guess at this point. The truck shifts flawlessly in all gears, just no overdrive.....anyone have any suggestions?
May 27, 2015 at 8:27 AM
