Nissan Repair: nissan skyline gearbox problem, lockup torque converter, nissan skyline

Question
hi i have a 1994 nissan skyline 2.5 turbo auto.
I'm having problems with the gear box as its not going into to top gear the revs just hit the rev limiter at about 70mph. the over drive is working fine as is the manual change 1st and 2nd gear. hopeing you can help

Answer
Craig,

4th gear is the overdrive if you have the 4 speed automatic transmission.  The way the system works is the car will not shift from 3rd to 4th until the car is at operating temperature.  Then, the overdrive (4th) will engage and then the lockup torque converter will apply.  So, you either have a temperature sensor that has failed or the vacuum sensor that detects a ligth load has failed.  4th and the lockup torque converter will not apply unless these conditions are met.  Now, be sure the throttle position cable is in good order by checking the tension, engine off, and someone pressing the throttle to the floor.  Open teh hood and feel the tension on the throttle position cable.  This is not the throttle cable but the one that feeds down to the transmission.