Error Code PO753

OK, This is my first real problem in 4 years with this Blazer.  Long story short, I need help narrowing down a SES light code of PO753.  I know it has something to do with the Trans., but have been given several possible causes by the parts stores.  Autozone says the shift solenoid, and they have 3 different listings ($45; $26; $30) and they did not know which one, or where they were located (Haynes was no help).  Checker had same code but said it was Trans. Modulator ($140) and could not tell me where it was.  The reason for this issue is that my wife drove about 200 miles in 4WD, and didn't realize it.  She called when the SES light came on and told me there seemed to be a loss of power.   I had her check the usuals (oil, trans fluid, coolant, etc) which all came back fine, so I told her to drive it home and I would look at it when she got here.  She arrived, and I took it for a drive and about 1/2 block away realized it was in 4WD, Took it out, and seemed to fix the problem, except the SES light stayed on, and the shift points for the trans seem to be off.  Any help would be great, and I will be watching the sight most of the day.

Here's what I was able to find:

quote:

CIRCUIT DESCRIPTION
The 1-2 Shift Solenoid (SS) valve controls the fluid flow acting on the 1-2 and 3-4 shift valves. The solenoid is a normally-open exhaust valve. With the 2-3 SS valve, the 1-2 SS valve allows four different shifting combinations. The solenoid attaches to the control valve body within the transmission. The 1-2 SS valve receives ignition voltage through circuit 1020. The Vehicle Control Module (VCM) controls the solenoid by providing the ground path on circuit 1222.

When the VCM detects a continuous open, short to ground or short to power in the 1-2 SS valve circuit, then DTC P0753 sets. DTC P0753 is a type A DTC.

CONDITIONS FOR RUNNING THE DTC

    * The system voltage is 10-19 volts .
    * The engine speed is greater than 450 RPM for 5 seconds .
    * The engine is not in fuel cutoff.

CONDITIONS FOR SETTING THE DTC
DTC P0753 sets if one of the following conditions occurs for 5 seconds :

Condition 1
The VCM commands the solenoid ON and the voltage feedback remains high (B+).

Condition 2
The VCM commands the solenoid OFF and the voltage feedback remains low (0 volts ).

ACTION TAKEN WHEN THE DTC SETS

    * The VCM illuminates the Malfunction Indicator Lamp (MIL) .
    * The VCM commands D2 line pressure.
    * The VCM inhibits 3-2 downshifts if the vehicle speed is greater than 48 km/h (30 mph ).
    * The VCM freezes shift adapts from being updated.
    * The VCM records the operating conditions when the Conditions for Setting the DTC are met. The VCM stores this information as Freeze Frame and Failure Records.
    * The VCM stores DTC P0753 in VCM history.

CONDITIONS FOR CLEARING THE MIL/DTC

    * The VCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
    * A scan tool can clear the MIL/DTC.
    * The VCM clears the DTC from VCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.
    * The VCM cancels the DTC default actions when the fault no longer exists and/or the ignition switch is OFF long enough in order to power down the VCM

DIAGNOSTIC AIDS

    * Inspect the connectors at the VCM, the 1-2 SS valve and all other circuit connecting points for an intermittent condition. Refer to Testing for Intermittent and Poor Connections in Diagrams.
    * Inspect the circuit wiring for an intermittent condition. Refer to Testing for Electrical Intermittents in Diagrams.
    * Refer to the Shift Solenoid Valve State and Gear Ratio table.
    * A faulty ignition switch may set this code.

There is a rather lengthy diagnosis flow chart, however it requires the use of a Tech2 or equivalent scan tool.  Here is a schematic showing the location of various components on the valve body:

I am pretty good, but I do not have a scan tool.  Can anybody simplify this flow chart?  Also can I reach the parts in the diagram by dropping the pan, or do I have to drop the tranny?   And is it the 1-2 / 2-3 / 3/2 ss that I need to replace?

Is this the correct part?   http://autozone.com/R,APP909128/vehicleId,/initialAction,partProductDetail/store,/partType,00623/shopping/partProductDetail.htm
 
I am under the impression that both of the solenoids in the rear of the trans are the same part.

*page not fount*

Anyway, yes, the 1-2 and 2-3 shift solenoids are the same PN (GM PN 24230298).