Toyota Repair: 1996 Corolla P0770 code, corolla dx, toyota technician

Question
Hi.  I purchased a 1996 Corolla DX 1.8L from my g/f, went to go get it e-checked, and it failed because check engine light would NOT light.  Turns out the bulb had been removed.  So of course when i swapped a bulb in the light comes on >.<  My girlfriend drove this car for 3-4 years, no problems, and i'm certain she didn't take out the bulb.  Rebuilt Salvage title, so whoever had it before I'm certain took it out.  Anyways, i need to get this light off to pass e-check, and other research i did lead me to believe this may be a problem with #3 solenoid.  So my question is, what might be setting off the P0770 code, shift solenoid circuit e malfunction.  Also, how much might it cost if I have to replace the solenoid?

Answer
This code refers to the shift solenoid that controls the lock-up torque converter, it's also called the "SL" solenoid, try replacing it, the whole thing may cost around $300-350 parts and labor. It may be a good idea to have the toyota dealer diagnose it and have them make a recommendation, it is also possible that there is a malfunction with the transmission that is causing the torque converter to not lock up when it's supposed to, a toyota technician can connect a scantool and activate the solenoid manually to see if the solenoid is working and if lockup occurs.