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Discussion Starter #1 (Edited)
So recently my RE4R01A (auto) transmission stopped holding 4th gear. Kinda odd problem, and has quite a few people stumped (haven't opened it up yet b/c I'm a 70 hr/wk person who must have their car), but basically when the car's warmed up (most of the time.. the problem's pretty sporatic) and I'm driving 55+ the car will shift into 4th when I'm accelerating, but as soon as I let off the gas (release the fluid pressure in the tranny) it drops back down to 3rd. Shifts perfectly, just refuses to hold 4th unless I'm accelerating. Opened trans pan, no scrap metal, and like I said it does shift perfectly - not ruling bad transmission out, but not likely. Checked TCU/ECU scanner, and the ECU shows I'm in fourth when I'm really in 3rd, so ECU is working fine. Solenoids A & B are opening/closing properly. Only problem that really catches my eye is the Clutch Overrun Solenoid isn't working. That's our first course of action, but I wanted to get some second opinions before I have the work done b/c it doesn't quite make sense that that would be the problem. Codes I've gotten back are: Clutch Overrun Failure, throttle Position Sensor (seemed to work fine when I double-checked it w/ the scanner), and knock-ping sensor (bay 1). I currently drive w/ overdrive turned off, but I did start to notice some slipping b/w 1 & 2 on inclines when overdrive is on (only after the problem started, perfect until then and problem did occur suddenly, not a gradual thing). This car is my life (fulltime student + employee) so any help would be appreciated.

Car Specifics: '95 240sx Base w/ Auto.
 

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justifide224 said:
the car will shift into 4th when I'm accelerating, but as soon as I let off the gas (release the fluid pressure in the tranny) it drops back down to 3rd. Shifts perfectly, just refuses to hold 4th unless I'm accelerating.
Car Specifics: '95 240sx Base w/ Auto.
Had something similar on my 240sx; turned out to be a bad TPS; the resistance track had a bad spot right around the position that it would be at when the tranny would normally shift into 4th.
 

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Discussion Starter #3
Interesting... I'll definately check into that ASAP. Appreciate the feedback.
 

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rogoman said:
Had something similar on my 240sx; turned out to be a bad TPS; the resistance track had a bad spot right around the position that it would be at when the tranny would normally shift into 4th.
After talking w/ my mechanic and thinking on this, it's safe to assume that it's not the TPS causing my problem. Reason being: the scanner shows my car as being in 4th gear when it's really in 3rd. If it were the TPS the computer would be responding to the data (whether acurate or not) transmitted to it by the TPS when selecting the appropriate gear, which would in turn be reflected by the scanner. Any other suggestions? :\

Faulty transmissions suck.
 

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justifide224 said:
After talking w/ my mechanic and thinking on this, it's safe to assume that it's not the TPS causing my problem. Reason being: the scanner shows my car as being in 4th gear when it's really in 3rd. If it were the TPS the computer would be responding to the data (whether acurate or not) transmitted to it by the TPS when selecting the appropriate gear, which would in turn be reflected by the scanner. Any other suggestions? :\

Faulty transmissions suck.
The transmission controller has a series of diagnostic tests which are described in the FSM; you might try running through them.
 

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Discussion Starter #6
rogoman said:
The transmission controller has a series of diagnostic tests which are described in the FSM; you might try running through them.
I think I know what you're referring to (flip ECU to test mode, put tranny in power shift mode, watch the 10-string series of flashes from the "Overdrive Off" light like a hawk and match the morse-code type fashes w/ the appropriate code), and if that's what you're referring to I actually used a handheld scanner (plugs into the driver's-side fuse box and interprets signals from the ECU) that electronically interprets those codes the TCU would produce (which aren't stored w/i the TCU, rather the ECU oddly enough) to a nice, easy to read LCD. The codes I mentioned above are the ones that were shown by the ECU, which is what I'd get from switching the transmission to diagnostic mode. I got a quote for a rebuilt transmission replacement - $1350ish w/ lifetime warranty, replacing w/ a factory rebuilt tranny & replacing the torque converter. At this point in time I think that's the best route for me to go ;(.
 
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