i have a 1996 toyota corolla that this winter started a delay in shifting into over drive untill after it worms up for 5 min or so
Year: 1996Make: ToyotaModel: corollaEngine: 1.8
had transmission checked and serviced,replaced the temp switch and gauge switch
it is normal operation for the overdrive on your vehicle to not come on until the coolant temp reaches around 155 degrees.
if you have a temp gauge on your dash,this should be approx. when the temp gauge is just over the 1/4 mark.
if the temp gauge is taking too long to reach over 1/4 or get to normal operating temperature which is close to the center of the gauge,you may have a bad thermostat.
if you have further questions or need more info on this let me know
toyota certified master diagnostic technician ase and hybrid certified