2002 blazer 4x4,changed transmission filter and oil,now i have a code po756,had trouble getting the pan back on,must have screwed something up,seems like tranny is slipping,ok in 1st ,second and drive slipp

 

Might have:

DTC P0756 = 2-3 Shift Solenoid Valve Performance

It's a Type 'A' Diagnostic Code:

The DTC Type Definitions contain the characteristics for all types of DTCs. Each DTC type may or may not be found in this section. The DTC type is based on the action that the PCM takes when storing DTC information and whether or not the PCM illuminates a service lamp or displays a message on a driver information center (DIC). The DTC descriptions in the Diagnostic Trouble Code List/Type are listed in numeric order and indicate the DTC types for domestic and export vehicle applications. Each DTC is categorized into one of the following types:

Type A
This DTC is emissions related. The PCM stores the DTC in History, Freeze Frame and Failure Records during the first trip in which the conditions for setting the DTC are met. The PCM also illuminates the malfunction indicator lamp (MIL) during the first trip in which the conditions for setting the DTC are met.

 

So what have i got myself into,i think i have to pull the pan again

 

It's possible that you messed up the wiring for the 2-3 shift solenoid when you did the filter swap. It is quite easy when trying to fit the pan back up between the trans crossmember and the valve body. If you did mess up the wiring harness, you may have to purchase a new harness.

Here is a schematic of the valves in the transmission:

 

Thanks for your help,i broke a shift solenoid new one $34.00

 

I'm glad that we could help!