Friend has a 92 loyale sedan push button 4x4. If you crawl under the car and manually put it into 4wd it works but not by the push button. If you have it in 4wd and push the button it will go into 2wd. Any ideas?

bad solenoid, or broken nipple on that solenoid

Just behind the driver side strut tower are two solenoids that open/close the vacuum to the 4wd on the tranny. Make sure there are no vac lines unplugged in this area. I can post a pic if it would help you.

yes please post pics

Yellow arrow = These are the solenoids.

Green arrow = There are two plugs like this, one for each solenoid. Make sure they're plugged in.

Red arrow = This hose supplies the vacuum from the engine. Check it to make sure you have vacuum up to this point. If not, this is your problem.

Blue arrows = These hoses go to the 4wd switcher on the tranny. Fwd/4wd depends on which one has vacuum at the moment. Make sure they're plugged in at the tranny. If they are, and it's still not working, try swapping them on the solenoids.

during 4wd, one solenoid is on, and the other one is off. When 2wd, the solenoids switch roles, so the one turns off, and the other one turns on.