tbear Posted January 14, 2007 Share Posted January 14, 2007 Hi maybe someone can help me with this problem I have. I own a 1991 Pathfinder VG30 engine with the RE4R01A Tranny I have had problems since I bought the truck with it staying in lock up. The tranny failed (Clutches) I rebuilt it replaced all of the solenoids in it during the rebuild, also put in a shift kit. I still have problems with it staying it lock up. This is how it works, Shifts good to 2nd, Drive and OD, after a while 2-3 miles it will go in lock up for about 1/4-3/4 mile (sometimes it goes in and out before staying in) and drop out and will never try to engage again unless I switch it off for about 30 seconds and once agian the proccess starts over. whether I switch off while coasting on stop and switch off and start again. I bought a book when I built the tranny and I check the computer and it told me it had a bad revolution sensor. I have called several nissan places and some do not even know what that is. The only other thing that does not work is the Tach? The only thing I gained by the rebuild is replacing the worn clutches which I think this maybe caused by the lock up problem. If you can help please let me know. Thanks, Ted Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 14, 2007 Share Posted January 14, 2007 You could try swapping the TCU. Those do go bad from time to time. The rev sensor is on the tranny....hmmm. *goes and looks* Top side at the rear. Link to comment Share on other sites More sharing options...
sw Posted January 15, 2007 Share Posted January 15, 2007 is the output of the revolution counter electric or mechanical? if electrical i would be putting a voltmeter across it and go for a drive if its any thing like a vss it will have a pulsed voltage that changes with speed let us know if you get anything Link to comment Share on other sites More sharing options...
tbear Posted January 15, 2007 Author Share Posted January 15, 2007 Where is the computer for the tranny located? I know I have a computer under the passenger seat???? Thanks, Ted Link to comment Share on other sites More sharing options...
tbear Posted January 15, 2007 Author Share Posted January 15, 2007 I think it is electrical the best I can remember. I know I have a sensoe on the rear axle which is the speed density sensor the best I can remember. Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 15, 2007 Share Posted January 15, 2007 It is electrical. The speed sensor is a magnetic reed switch that feeds the ECU voltage pulses so it can calculate your speed. The rear diff sensor is for the ABS. The TCU is behind the wall panel in the rear under the window on the passenger's side(US passenger, heh). It's gold anodized/plated with three mounting legs and two wiring plugs IIRC. Link to comment Share on other sites More sharing options...
tbear Posted January 15, 2007 Author Share Posted January 15, 2007 Hi cant remember for sure but is the revolution sensor on the tranny or the transfercase of this truck. I guess I will have to clean some mude from under it to find out. Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 20, 2007 Share Posted January 20, 2007 Like I said above, top rear of the transmission. Link to comment Share on other sites More sharing options...
tbear Posted January 24, 2007 Author Share Posted January 24, 2007 Hi 88pathoffroad I got a guy to send me a revolution sensor what he sent me was one of the 2 on the transfercase. It was the one that is on the side of the transfer case (passenger side) not the one that is on the top just above it which I think is the one that shows that it in 4 wheel drive. I dont see one on the tranny itself. You wouldnt have a pic that could show me where it is do you? Any help would be appreciated. Thanks, Ted Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 25, 2007 Share Posted January 25, 2007 According to my 88 FSM, the two switches on the t-case are for neutral and 4WD indicators, like you said...(probably the same for a 91, they didn't change much drivetrain-wise) Here! Piccie. Link to comment Share on other sites More sharing options...
tbear Posted January 27, 2007 Author Share Posted January 27, 2007 Just to let you know I have replaced the revolution sensor Tranny computer and it still falls out of lock up?????? I did not reset the computer after I replaced the revolution sensor! Maybe I will disconnect the battery and see if that might help. I dont know if I told you but the tachometer does not work either???? I am going to look in the wiring diagram and see if they are connected in anyway? I am pretty sure it works I removed the cover on the cluster and moved the needle up, when I cranked the truck it went back to 0 and bobbled. If you have anymore ideas up your sleave let me know. Thanks for all the help Ted Link to comment Share on other sites More sharing options...
TrailChaser Posted January 28, 2007 Share Posted January 28, 2007 The RPM's(tach) shouldn't have anything to do with the tranny. Maybe if you get the tach working the ecu will know what's going on and then maybe it'll stay locked up. My tach never stopped working when I swapped out the automatic tranny for a 5 speed. I do however have a check engine light that I can't get to go out because the ecu doesn't know how fast the truck is moving. (Speed sensor code 14) Link to comment Share on other sites More sharing options...
tbear Posted January 29, 2007 Author Share Posted January 29, 2007 Hey anyone got the instructions on checking the tranny computer? I had them in a ATSG manual I had but now I cant find the book. Its got the wiring diagram I needed for the tranny in it also. I any of you guys can help I would be grateful. Thanks Ted Link to comment Share on other sites More sharing options...
88pathoffroad Posted January 30, 2007 Share Posted January 30, 2007 There's a pinned topic in the Garage on how to do that. Link to comment Share on other sites More sharing options...
terryzrx1200 Posted February 23, 2007 Share Posted February 23, 2007 How hard is it to get to the revolution sensor. Manual calls for the removing the transmission mount and supporting it with a jack, then lowering the transmission as far as you can. Is this the only way to get to the revolution sensor? thanks Terry Link to comment Share on other sites More sharing options...
88pathoffroad Posted February 23, 2007 Share Posted February 23, 2007 Yes. It's right under the floor of the body otherwise. Link to comment Share on other sites More sharing options...
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