4T60E Trans Trouble

[chevycountry88]

Hey guys, The car is a 93 Chevy Lumina Euro. I'm wasn't sure what it is. I changed the Speed Sensor today, but it's still doing the same thing. The wife said that when she takes off it doesn't want to shift out while in drive, but you can manually shift it, and it does alright for a little bit. While in town she's doing 35 or so, it got up to about 3 grand and she felt it kick in, and was able to speed up leaving town, the service engine light comes on. She knows she running at least 45 to 50 and the speedo shows between 10 and 15, then all of a sudden it will jump up to 45 or 50. Then when she has to slow down to go into another town it starts all over, it doesn't want to shift out. She can sometimes pull over run it through the gears and get going again. Anyone have any advice?? Thanks!!

[maxwedge]

Welcome to AF, I would scan it ans see what mph the pcm is seeing.

[chevycountry88]

Originally Posted by maxwedge

Welcome to AF, I would scan it ans see what mph the pcm is seeing.

Thanks for the quick reply! I did not have a diagnostic, so we just used the key and it kept flashing 12.

[maxwedge]

12 means there are no codes, the scan with a trans function scanner is a different operation.

[dannym]

The vehicle speed sensor, located on the transmission, sends electrical pulses to the dash instrument cluster for the electronic speedometer stepper motor to function, those pulses are then sent to the ECM, engine control module (computer) so that it can use that data as to determine engine timing and mixture values, as well as to tell the transmission when to shift. It appears that your speedometer being erratic is an indication that the pulses from the VSS are not indicating proper vehicle speed. Changing the sensor is easy. It is located on the back bottom of the transmission, passenger side. Remove the electrical plug, and then the bolt that hold it in, replace with a new unit. If that does not fix the problem, the instrument cluster may have faulty connections, which are not letting the signal get through to the ECM.

[maxwedge]

Again, old inactive thread.

[dannym]

Old and inactive, but someone might read it for current information.