Truck lacks power in first gear. Shifts into 2nd smooth but at high RPM 4-5k and very slow speed. Will still shift into 2nd at WOT but truck won't gain much MPH. All other gears shift normal and smooth including reverse. Has no problem in higher gears getting to highway speed. Downshift fine when coming to a stop. But take off again climbs RPM and slow speed. Has no problem performing passing manovers at highway speeds. Can manually shift from D1-3 fine.
8000 miles ago had the transmission flushed with new filter after the extender housing was replaced. No metal in fluid and was clean.
Problem just started randomly one afternoon.
Would a bad front prop shaft speed sensor, one on top of transfer by front drive play a part in this? Has a usual wear on wire and possible bare spot.
Could this be electrical speed sensor, shift solenoid, throttle position sensor or is my 4L60E roast? CEL throws 02 code
My car has 200000 miles.
My car has an automatic transmission.
Hi there. It is very possible that the speed sensor or shift solenoid is the primary source of this type of issue with the first to second shift. However, a worn out torque converter or an obstruction inside the transmission hydraulic lines can also produce similar symptoms. Since you recently had the fluid and filter changed, it would expect the sensors as being the primary culprit. I would suggest having a professional mobile mechanic come to your location to complete a Check Engine Light inspection, as the code you offered is a specific GMC code that indicates a general transmission problem. The detailed CEL inspection will download the OBD-II codes that we need to accurately determine the source.