Check Engine Light

[fromundr]

My check engine ligth came on in my 96 LS400, at the same time the Power ECT light started blinking on and off. Read the code and got a P0770 whci the scanner said was a "Shift Solenoid Malfunction" What is this and can I change it myself. Looking for the code online I found a description of "Lock-Up Solenoid Fault." The cars runs fine but ever once in a while when I slow down and then try to speed up, it begins to shudder and vibrate as if it had not downshifted and it has a hard time accerating. Any help or advise would be greatly appreciated. Thanks in advance!!

[VMF]

The ECM uses the signals from the NCO revolution sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SLU, valve body and torque converter clutch.

[VMF]

here is a check procedure

[VMF]

and here is the final picture

[fromundr]

Thanks!! From the detection condtion supplied, it sounds like my lock-up remains on and when i slow down in traffic it does not down shift and vibrates as if in the wrong gear until i pick up speed. Where would I find the valve so I can perform the test? Is it near throttle body or located on transmission? Once again all input really apprerciated and thanks in advance!!