I have 1995 Toyota Avalon w/173K miles. It’s in good shape mechanically and cosmetically. It was my father-in-laws car who purchased it new. He’s a cheapskate and couldn’t bring himself to give it to his granddaughter, I had to buy it from him for a princely sum, well not so princely, but more than I wanted to pay. My 16 yr old daughter is the primary driver.
I have extensive service records and have replaced the springs/struts, o2 sensors, and a few other bits.
My question is related to hard shifts and a check engine light. During the summer the trans shifts normally. In the fall & winter (Chicagoland), when temps dip below 50 degrees, the trans shifts harshly and the check engine light blinks indicating a trans solenoid is defective. The trans fluid has been flushed twice, most recently in Oct 2008 at the Toyota dealership. My theory is the techs filled the trans with a heavier weight fluid than is necessary and that is triggering the codes.