SteeringTemporarily Incapacitated in a 1998 Toyota Corolla automatic

What is causing this problem?: Twice when I’ve been coming home in rainy weather I’ve lost steering of my car in the exact same location. I make a very sharp right up a small, narrow but very steep hill. The road levels out and at the stop sign I attempt to make a left hand turn but the car barely manages the turn even though I’m turning the steering wheel as much as I can. The battery light comes on and with equal difficulty I make a laborious left turn into my driveway and park inside the garage. The steering is normal again by the next day. After the first incident, the mechanic said the Serpentine belt was fine but that a water guard was loose so he tightened it. Immediately after picking the car up I drove around in heavy rain for a few hours and made it home without a steering problem though my route didn’t include that steep little hill. Then I drove the car around in dry weather for 3 days with no steering problems anywhere. The second incident happened 4 days after I got the car back from the mechanic. Both incidents happened when the car was out in the rain for at least 40 minutes and I went up that steep little hill. I’ve been driving the same routes for over 4 years now in all kinds of upstate NY weather and this has never happened before. I’m loosing trust in the safety and performance of my loyal Toyota which has been with me for 100,000 miles. Please help me keep the faith!

If the alternator light comes on at the same time the steering becomes difficult, it indicates the serpentine belt is slipping when it gets wet. This could be caused from a worn serpentine belt, and/or a worn serpentine belt tensioner.