Toyota Repair: shift solenoid, toyota 4runner, metal contamination

Question
I have a 1998 Toyota 4runner, V6 with automatic transmission and 115,000 miles. Recently the "check engine" light illuminated. I took it by a local auto parts store to read the code, and was told the shift solenoid had a short to ground. The vehicle runs fine, with no obvious problems. Where is the shift solenoid located and what does it do?

Answer
I need to know the trouble code to know which shift solenoid may be the cause, there are 4 solenoids on this transmission so it makes a difference which one may be the cause, by the way, all of the solenoids are inside of the transmission attached to the valve body, in most cases the solenoids are not the problem but rather impending transmission failure, if there is metal contamination in the transmission fluid it can cause the solenoids to stick and malfunction due to metal contamination, I would recommend having the transmission oil pan removed at this time to make sure there are no metal particles in the bottom of the oil pan.