mcmaklin

I need help with Closed Throttle Position switch I think, but maybe you know what could cause the problem, I am not sure.
I own Maxima QX 2001 3l engine, AT, A33 Japan Europe.

Sometimes I have problems with AT, once I ended even with a P0731 error that I deleted.

I have some problem when I start the engine and go from P to D or R, sometimes just after switching on my engine I can feel that it is very hard to move to R and there is a big jerk also when moving to D. When I turn engine off and start it again everything is normal. But when I ignore the error and start driving, there is a big jerk when my car tries to switch to 2nd gear.
Because several months ago I was changing TPS now I can see something prevents from putting Maxima in the mode when AT light shows error codes (it was not also possible to do this when the closed throttle connector was disconnected, I had some another problems before that needed to disconnect this commetor), so I am not sure if this switch is functioning.
The manual says:
A closed throttle position switch and wide open throttle position
switch are built into the throttle position sensor unit. The wide open throttle position switch is used only for A/T control.
When the throttle valve is in the closed position, the closed throttle position switch sends a voltage signal to the ECM. The ECM only uses this signal to open or close the EVAP canister purge volume control solenoid valve when the throttle position sensor is malfunc- tioning.

It is the lowest connector as far as I know.
"A closed throttle position switch and wide open throttle position
switch are built into the throttle position sensor unit" - is it the same the lowest connector (there are 2, the upper is Throttle Position Switch)"

Please help me to identify the problem, MAXIMA is a rare care here in Europe, thanks!

andrewmac

iTrader: (2)

If you have small hands then just unplug the TPS and take a ohmmeter and measure the resistance across the top two pins in the top connector on the TPS itself. It should decrease as you open the throttle with your hand. Then the top two pins in the bottom connector should have continuity when the throttle is closed, and none when its open just slightly. When I was doing mine I just took a piece of thin cardboard from a cigarette pack, folded it twice, and put it in the stopper on the throttle to keep it slightly opened then turned it until I lost continuity.

Its a tight squeeze though so if you get frustrated just take the stupid thing out and check it to make sure its working.

DennisMik

iTrader: (2)

To start with, you seem to have 2 problems - the transmission and maybe the TPS.

You are trying to run the transmission self diagnostic because you had the OBD code of P0731. If you have the Nissan FSM (Factory Service Manual) and look up code P0731, you would see that you are wasting your time. This is from the Nissan manual for code P0731:

* This is an OBD-II self-diagnostic item and not available in TCM self-diagnosis.

* This malfunction will not be detected while the O/D OFF indicator lamp is indicating another self-diagnosis malfunction.

* This malfunction is detected when the A/T does not shift into first gear position as instructed by the TCM. This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

If you want to download a Nissan FSM for your QX model, go here:

http://www.nicoclub.com/FSM/maxima/2000/

the automatic transmission section is AT.PDF. The self diagnostic section starts on page 49 and the P0731 code is on page 144.

mcmaklin

Thank you for ALL your help!

<Andrewmac: "If you have small hands then just unplug the TPS and take a <ohmmeter and measure the resistance across the top two pins in the top <connector on the TPS itself. It should decrease as you open the throttle <with your hand


I am asking about the lower connector. I am sure the upper Throttle Position Sensor does work well.I assume the lower one doesn't work because there is even no way to enter into AT diagnosis mode but it was possible to do before. The TPS is new and is 6 months old.


"You are trying to run the transmission self diagnostic because you had the OBD code of P0731. If you have the Nissan FSM (Factory Service Manual) and look up code P0731, you would see that you are wasting your time"
I was just trying to run the transmission self diagnostic because I wanted to make sure that 0 position switch works. As far as I remember it was not possible to enter self diagnostic at all when its plug (lower, brown) was disconnected, and also my car had similar problems sometimes. (About half a year ago after changing the TPS I had some problems that when my car was shifting from 2nd to 3rd gear there was something like a slide down from upper engine speed - it has just disappeared after I disconnected the Position Switch Connector and then after I reconnected after a day everything went to normality)


"This is not caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc"

How can I check proper solenoid valve operation, where is the solenoid valve there? My car goes on Monday to someone who should be able to do this, but as I said, it is a rare car here.

DennisMik

iTrader: (2)

The solenoid control valves (there are 4 or 5 of them) are inside the automatic transmission. As far as testing to find out if these valves are malfunctioning, I believe there is a proceedure in the FSM. Maybe you should print a copy of the FSM and give it to your mechanic. If he works on automatic transmissions, he should have no problems following it.

mcmaklin

Thank you, maybe you can tell me where in manual there is a way to test solenoid valves- but maybe first I should just check somehow the close throttle position switch