NIssan Sentra overdrive (Page 1/1) heybjorn FEB 17, 12:42 PM I have a 98 Nissan Sentra which has started taking a long time to shift into overdrive. Normally it does this at 41-42 mph. When it shifts up the slightest lift of the throttle or incline in the road will cause it to shift back down. I havehad it not shift into overdrive at all, getting up to 60 mph before I lifted the throttle and tried again. This has only happened twice. My mechanic said all of the external electrical connections are good. He thinks the the lockup solenoid is bad. The shop transmission shop he sent me to said 10,000 more miles at most and the trans is gone. All the other gears work, goes from park right into first and shifts like it should up to 45 mph. Any ideas? carnut122 FEB 18, 11:59 AM I suspect there's a cable adjustment or vacuum hose/diaphragm that detects when you are "flooring it." I would start there as it sounds like your transmission is receiving a signal it is under greater throttle angle than it is. Not sure if your TPS might have anything to do with this, but the fact that it does shift into OD and that gear seems to work makes me think the problem won't lead to failure within 10,000 miles. cmechmann FEB 21, 10:03 PM Most are computer controlled after 93. There are tap ports on the trans to see if pressures are applied to the clutches, but few go that route. Borrow a scanner that can bring up trans data. You should be able to tell if/when each upshift is applied. Or you can see if something else is causing it not to upshift. Coolant temp too low, TPS too high, Speed sensor too low, ect. If it looks OK from there. Get a wiring diagram. The solenoids are normally controlled from the ground side. With the trans connector disconnected, apply 12v to the common supply terminal. Then one at a time apply ground to each solenoid terminal. You should be able to hear each "click". Then if that turns out OK, you know you have an internal clutch problem. It does not have to be the 3/4 clutches going out. You could have 1/2 or 2/3 clutches going out. Any one of them would make it feel like you don't have your final gear. Instead of 1/2, 2/3 then 3/4 it would go something like 1/2, 3/4. Because you lost 2/3 if would feel like you lost 4th.