wikd240

i have a 93 coupe with an auto transmission... i am having some problems with it shifting... sometimes it will shift perfect no problems... other times it will not **** out of first gear and then other times it will never go into first even if you shift it manually...

there is also another thing... when i start my car if the od off light flashes the transmission will act up... if the light does not flash then it will shift fine... anyone know what the problem is or if there is a diagnostic step for the flashing od off light...

i have checked and changed the trans fluid in my car and that did nothing to help...

any info would be great...

Joel SX

http://www.club240.com/forums/showth...threadid=25916

That thread should help you identify whats wrong with your trans. It turns it to diagnostic mode.

wikd240

yeah i posted it... lol... that is what i found in my search for answers...

wikd240

i have fixed my problem... first off it was not in the speed sensor the rev sensor or in the transmission ecu... the problem was that the signal from the speed sensor goes from the transmission to the digital speedometer then to the trans ecu... with a non functioning digital speedo (my attempt at repairing the unit caused other damage) stopped the speed signal getting to any other part down stream from the speedo...

so my fix was... i replaced my digital speedo with an anolog unit out of an 89 hatch... swapped out the wiring harness and the tach and it works shifts and functions as it should...

Joel SX

Well good for u. Now here's my problem. My Speed sensor is leaking oil, and I've been told by the mechanic to change it. the car reads the speed ok, mine is a digital heads up dysplay too. About a year ago I discovered the thread about cutting the speed sensor wire, so I unpluged my speed sensor and I had no speed (but incredible speed at top end). then I pluged back on so I could see the speed, then cut the speed sensor wire that goes to the ECU, not the TCU. It worked fine for about a year. The speed limiter didn't worked and life was good. Now that problem came up were my trnas won't go into any gear, only 2nd and reverse and park. It won't lock out of park. the OD light doesn't come up in any way, won't go into diagnostic, the OD button is useless, it goes into a sort of 1st If I put it in 1st. but fro mexperience I know that in 1st it should have enough power to burn out wich doesn't. I've tried reseting the ECU and soldered the cable back on. the ECU says code 54: ECU to ATC unit circuit. I've cheked all the cables from one ot the other. Disconected both and re-conected. the speed sensor works because I can see the Speed in the digital thing, and the ECU doesn't give me 14: Speed sensor circuit problem so what the hell is wrong?!??!

I think I burned the ECU not the TCU, because the other day I was trying to hook it up to this OBD1 plug and the nissans use some other conector, very diferent. So maybe its burned and It can't comunicate with the TCU. I've cheked ALL fuses and relays that have to do with the system. I'm not goign to buy another ECU becuz is probably so much, I can buy a new stadar Tranny and I'm going for the RB25DET. Good thing my car broke, now I get to move on to better driving power :P

wikd240

if the ecu is giving you code 54 then that would tell me the ecu is functioning correctly... it is looking for the tcu which it cant find for one reason or another... i would say go to the junk yard and get another tcu... and replace the bulb in your od light... they are cheap and easy enough to replace... then check to see if your od light works again..

the other thing you said was that the ecu reads the speed sensor... so that is a good thing... it tells me that the ecu is functioning again... in the fsm on our cars in all of the trans diagnostics sections the repair was never stated as replace the ecu... the worset case has always been replace the tcu... from looking at the electrical schematics on the car every function on the transmission except cruise control and the speed sensor routes through the tcu befor it goes to the ecu... so my bet would be on swapping out the tcu for another unit and trying to get the transmission into diagnostics mode...

Joel SX

AHH!!!!!! I replaced the TCU, no luck, same crap, but this tcu was from a 91 model, they are compatible, same trans- same model (S13) and nothing, same thing. So I went and bough the ECU and pluged it in, no luck, I'm gona scan it, but if its the same thing (code 54) I'll have to chekc every single cable and switch and solenoid and blah blah blah. I HATE AT trans!!!!.