Transmission won't shift to od: '91 ay body

Question

My 1991 newyorker 5avenenue shifts gears good ,but tries 3 times to get into overdrive but wont go into it.I could at one time stop , put it in park restart engine and it would shift right in.is this internal or is it a sensor problem

Answer

Hi Ken, The best way to diagnose this problem is to do a fault code readout of the transmission controller memory using an OBD-I diagnostic box with a plug that fits the 6-pin blue socket under the dash on the left side lower panel area. Once we have a 2-digit fault code the possiblities will be delimited. I assume that you have checked the fluid level in the transmission and added ATF+4 if needed via the dipstick tube. So let me know what code number you get and we'll go from there. Unless it is something that is repairable without removing the transmission, the most econimic option may be to accept the situation because the economy offered by OD would not overcome the cost of a rebuild. Please 'rate' my answer (see below). Thanks, Roland