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Diego Hei...
Points: 10

What can cause a transmission to not shift?

I have an 02 nissan altima 2.5s automatic and just recently repalced the motor and was able to get it work, but I am having trouble with the transmission. it goes into reverse, neutral, and drive fine, but wont shift when i start driving. it doesn't get out of 1st gear. once i reached like 20 miles an hour the rpm gauge goes up without going any faster. the engine light came on, and it said the variable speed sensor, so i replaced it and the engine light is off now, but still wont shift. it has transmission fluid. any idea what it could be? anything advice/ idea helps. thanks and appreciate it

3 years ago

4 Answers

Points: 3

The transmission that is in your vehicle is a RE4FO4B, the problem your explaining sounds like the transmission is flaring. If when driving it feels like the vehicle goes into neutral their is a pressure issue inside. It may be as simple as a bad EPC solenoid, which is the electric pressure control, that would have to be checked via a scan tool with data flow and looked at by someone who is qualified to decipher the readings. I would have to think though that it is going to be an internal pressure loss, which means that one of the seals internally is not holding pressure. If this is the case there is no way around rebuilding or replacing the transmission.

3 years ago
Points: 1
1, 100% positive

You need to first check fluid condition not just level. I recommend changing fluid and filt and add an additive like Lucas.

3 years ago
Points: 1

You have a computer controlled trans so it will need to be 'scanned' to see if the trans is being commanded to shift or not. You might have unplugged the VSS [vehicle speed sensor] and if the computer doesn't know you are moving, it won't shift it

3 years ago
Points: 1

Snotrans is absolutely right. The tranny is shifted by a command from the computer. This will only happen if the computer receives the correct signal from the vehicle speed sensor. If the tranny worked fine before the engine swap, then an unplugged sensor, broken wire or connector, or possible blown fuse are the most likely causes. Always verify fluid level and condition also. Burnt smelling fluid indicates a slipping clutch. A good transmission shop can scan the car and find the issue.

3 years ago