AT Check . . . Please Help

[94J30]

I have had a flashing AT light since just after I bought the J a couple of months ago. I took it in to Nissan for a Diagnostic on the VTC system and had them check the AT light as well. They said it was the Vehicle Speed sensor code. Taking there word for it I just changed the sensor today and guess what. . . Check AT light. A little irritated I did the self diagnostic and got a engine control circuit error code and a Revolution sensor code I believe. Solid flashes on flash #1 and 12. I also dropped the pan, changed the filter and gasket and gave the pan a thorough cleaning. Well, since changing 4 1/2 quarts of fluid with new, It initially ran smoother. The 1-2 shift was much smoother but still crisp. Now, it is slipping when it is cold. Any ideas would be appreciated. The Revolution sensor is self explainatory enough but the engine control circuit has me clueless.

FYI, as far as I know this is the original transmission, 187K miles.

This is a similar thread to the one I posted in the J30 forum but got little feedback. I made a few changes on this one hoping to get a better response.

Thanks

[Q45tech]

The J30 shares AT with the non turbo 300zx [90-96] and a few other Nissans model number RE4R01A.

187K and 12 years in this application is a long and fruitful life.

[maxnix]

Try a complete chemical flush and mechanical fluid exchange.

http://www.bgfindashop.com

All you did was dilute the contaminated fluid slightly.

[elwesso]

yeah I think at this mileage it might be time to bite the bullet and get a new trans. fortunately good used ones should be easy-ish to find with the 300ZX

Dont know why it could throw the ECU circuit error unless you tried unhooking the ECU or TCU with the ignition on??

Im wondering if you have some bad wiring somewhere.

[94J30]

yeah I think at this mileage it might be time to bite the bullet and get a new trans. fortunately good used ones should be easy-ish to find with the 300ZX

Dont know why it could throw the ECU circuit error unless you tried unhooking the ECU or TCU with the ignition on??

Im wondering if you have some bad wiring somewhere.

Right. The FSM only mentions to check the continuity of the harness between the ECU & TCU really. Plus the connections. And or replace the harness. I have never messed with the TCU or ECU on this car.

My other ? is where is the Revolution sensor??? That is the other code it is throwing. Could a bad TCU be the problem??

Is the 300ZX Trans identical to the J's?? And could the Revolution Sensor and/or the Engine control circuit problem cause the trans to slip in first?? Or is that only mechanical failure.

I am trying to salvage any life left in this transmission.

[Q45tech]

Slipping is always a mechanical problem unless the TPS is misadjusted or he TCU receives an improper signal.

All TCU can do is adjust the duty cycle on ATF shift pressure solenoid to compensate for ATF temperature as it warms up.

A good chemical flush and 100% ATF [ 10 quart] exchange.

[94J30]

Alright, I finally had a chance to investigate the Engine control circuit code the TCU was throwing. After double checking all the connections at the TCU, the AT Fuse, and resetting the Computer, No more engine control circuit code. Only the Revolution sensor code which I will take care of in the next couple of weeks. Still trying to get the wifes heart rate back to normal after the VTC sprocket replacement during the 60K!Me>> <<My wife

[94J30]

Ok, I am in need of a bit of assistance. Where is the Revolution Sensor Located. In the FSM it shows the VSS on the tailshaft of the transmission being the revolution sensor. There are 3 separate AT errror codes for VSS, Revololution Sensor and Turbine Revolution Sensor. I replaced the VSS on the tailshaft already. I know where the TRS is located on top of the transmission but can't seem to locate the Revolution sensor which is the code I am throwing.

[Q451990]

If it's like the Q, the turbine revolution sensor is on top of the transmission near the firewall. Typically it requires dropping the transmission to get to it... not sure on the J though.

Heath

[94J30]

If it's like the Q, the turbine revolution sensor is on top of the transmission near the firewall. Typically it requires dropping the transmission to get to it... not sure on the J though.

Heath

I know where the turbine revolution sensor is. There is a separate error code for the TRS and the revolution sensor. I am throwing a code for the Revolution Sensor. Anyone??

[Q45tech]

The revolution signal is the engine rpm comes from ecu to tcu see your FSM.

[94J30]

The revolution signal is the engine rpm comes from ecu to tcu see your FSM.

I guess I'm not understanding what your trying to say. I understand that the revolution signalcomes from ecu to tcu but am unsure where to go from there. I was just going to replace the sensor.I looked in the FSM, it shows what I just replaced, the VSS as the revolution sensor. AT-100, Revolution Sensor replacement. Also, the pic under AT-80 for electrical component trouble diagnosis shows the VSS on the tailshaft I just replaced. Unless there is a similar sensor that I am not seeing, I can't locate it.

[Q45tech]

The Tcu receives 3 rpm sources: the engine rpm [which is the same as TC INPUT rpm]. The TC OUTPUT rpm [TC slip] from the top sensor. which is the actual transmission input rpm.

Finally the speed sensor which is the AT output rpm or the drive shaft rpm.

[94J30]

The Tcu receives 3 rpm sources: the engine rpm [which is the same as TC INPUT rpm]. The TC OUTPUT rpm [TC slip] from the top sensor. which is the actual transmission input rpm.

Finally the speed sensor which is the AT output rpm or the drive shaft rpm.

I thought there was a separate RPM sensor for this that I could just replace since that is the error code I am getting. I was trying to avoid having to dish out more coin for diagnostics since they said it was the VSS that was the problem, with an intermittant failure. I replace that and still had the Engine control circuit and Revolution Sensor codes on the Self Diagnostics. The Engine control circuit error is gone now and I'm left with the Rev Sensor code and no clue how to fix it. I am just going to have to take this in to a shop.