Originally Posted by gcnetspeed
2004 SUBURBAN c1500 4L60e will not shift automatically while in drive or overdrive, starts out fine but will not shift at shift points and just keeps revving no shift almost seem as it is in low (1st) gear changed VSS, no help... thinking about changing TPS but found out it can not be changed by itself it is part of the throttle-body and the whole throttle-body needs to be replaced to change the TPS...now thinking 1-2 2-3 solenoids might be clogged.....also tach not working properly and speedo not working (stuck at 85 mph) but have been not working for a while prior to this tranny problem???? any help greatly appreciated.
need a scan tool with a live data stream to see if the computer sees a speed signal and to see if the trans is getting command for shift. the dash can be messed up but as long as the pcm sees the proper speed signal, it will shift. also, just by changing the vss, doesnt mean that it was the problem, it could also have a wiring problem.
the other thought is if its got hi mileage, its possible that it may have internal parts failure and needs to be rebuilt. hows the fluid level and condition? any recent service work done to it? how many miles are on the vehicle?
if it neutralizes at point of where it would normally shift, that could very well indicate an internal failure.