Hello, My name isXXXXX am a Certified Auto Technician with 25+ years experience. I will do my best to assist you. I don't know your automotive experience level, so I may have to ask questions of you before I can answer. I only know as much about your concern as you have stated in your post, so please feel free to add as much detailed information as possible.
Which speed sensor did you replace? There is an input speed sensor and an output speed sensor, either one can cause this problem, also, an internal transmission failure can cause this problem, Have you scanned the vehicle for codes? If you have, post the codes here. If not, That is the next step that needs to be done...Sometimes you can get the vehicle to display the codes for you on the odometer, just cycle the key on and off 3 times and leave it on on the last try (ON-OFF-ON-OFF-ON), look at the odometer, and it may display "P Codes" write down all of them and post them here... Let me know the results...
How did you obtain these codes? These are all engine related codes except the P0700. But unfortunately you will need to scan the Transmission Controller (TCM) to be able to see what codes are stored in that module. I'm posting the flowcharts for all except the P1684, which is not showing as a valid code... Here they are:
P1491 - Click here to view
P0135 - Click here to view
P0300- P0302 - Click here to view
P0700 - Click here to view
We will need the codes as read from the TCM, you may need to take it to a shop that has a scanner that can access the TCM, a normal code reader will NOT be able to access the TCM. When you have the codes from the TCM, post them here and I will continue to help you with this concern.
It is VERY possible that the problem is actually the Input Speed Sensor, So if you like, you can TRY that next if you like, but actually I recommend getting it scanned first, post any Transmission Codes, and we can continue from there....
If you have any follow up questions, don't hesitate to ask, I am happy to help until your concern is resolved. Thank you and thanks for using JustAnswer!