I am having problems with my auto transmission!

It is stuck in what I think is 3rd gear and has loads of slip.

When you put it into 1st it does appear to be in first but again has slip.

Reverse works fine, park and neutral also okay.

Oil level looks okay and oil colour doesn't look too bad.

Conzult throws loads of errors:

TPS signal

VHCL SPEED SENSOR - A/T

TURBINE SENSOR

ENGINE SPEED SIGNAL

SHIFT SOLENOID VALVE - B

VHCL SPEED SENSOR - MTR

 

When travelling at speed and removing foot from accelerator, engine speed immediately drops to idle (no engine braking - lock-up)?

I'm thinking it could be the TCU is screwed but I'm really struggling to find a replacement to prove this.

The TCU part no is 31036-46P20 I've managed to find a second hand 31036-45P20 which I'm going to try.

 

Any advise gratefully received.

sounds like a wiring issue.

 

Are all 3 connectors from the main AT harness plugged in (firmly) ?

 

Thanks lymon.

I have checked the connections as you suggest and have sprayed them with contact cleaner.

I also took the opportunity while the solenoid harness connector was off to check the resistance on the pins as per the WSM.

The SHIFT SOLENOID VALVE A CIRCUIT read 24.4 ohms (should be 20 - 40 ohms).

The OVERRUN CLUTCH SOLENOID VALVE CIRCUIT read 24.4 ohms (should be 20 - 40 ohms).

The TORQUE CONVERTER CLUTCH SOLENOID VALVE CIRCUIT read 13.4 ohms (should be 10 - 20 ohms).

The SHIFT SOLENOID VALVE B CIRCUIT read 0 (should be 20 - 40 ohms) PROBLEM!!

 

Using Conzult I can see that Solenoid valve B is always on (solenoid valve A is on in 1st and goes off when changing to 2nd).

Conzult says its changing into 3rd and 4th but its hard to feel if you are and solenoid valve B is still on!

 

The Conzult A/T diagnostics report:

SHIFT SOLENOID VALVE - B

VHCL SPEED SENSOR - MTR

 

Conzult A/T data shows VHCL/S SE-A/T changes with vehicle speed and VHCL/S SE-MTR is stuck on 3mph and never moves. PROBLEM!

 

So questions:

How can I test the solenoid valves?

Where is the VHCL/S SE-MTR sensor and how do I test it?

the valve solenoids are inside the gearbox and you will need to remove the oilpan (and probably the lower valve body..can't remember) to get to the main connectors and solenoids

putting 12v on the terminals should make the solenoids "click"

 

Maybe best to try another ATCU first, before taking apart the gearbox.

 

the VHCL/S SE-MTR is the speed sensor on the side of the gearbox.

However if your speedometer is working correctly, it is probably not the sensor itself but something else, as it uses the same speed sensor.

When you monitor the engine ECU using conzult, does the speed reading work correctly there ?

Well I made a big step forward today when I discovered that the solenoid harness at the gearbox had been damaged at some point and replaced with individual crimp connectors but whoever fitted them had not actually crimped them and had just taped them up!!!

 

Several wires were loose and damaged. I reconnected them (with a terminal block temporarily - until I can source a proper connector) and - WOW! What a huge difference!!

I now have all gears and kick-down and everything, what a relief. Conzult is still reporting a problem with the VHCL/S SE-MTR.

I took the opportunity to remove it and test for AC 0.5 volts when spinning it by hand, I seemed to be getting it as a pulse which I believe is okay?

To answer your earlier question, my speedometer is working correctly but the Conzult A/T data still shows 3mph and never moves and the ECU data speed reading is also 0mph.

Other issues, which I think could be symptoms of the speed sensor are:

As you slow down (watching the gear changes in Conzult), the gearbox doesn't change down to 1st or 2nd unless you actually stop which makes the engine/gearbox labour until you get back up to speed (or stab the throttle).

The HICAS light comes on on occasions and the power steering goes, but Conzult reports no HICAS errors (stopping and starting the engine clears the condition temporarily).

 

I'm getting so close now, I just need your help sorting this speed sensor issue!!

 

There is still a bit of a whirring noise (and a slight vibration) from the gearbox so after all is sorted I think an oil and strainer change is in order, even if I have to order the set from Australia!

 

Thanks in advance.

the actual (digital) speed signal for Engine ECU, HICAS ECU and ATCU comes from the speedometer-cluster and not from the sensor directly.

 

so if you have a working speedometer, but no speed-indication on any of the ECU's (which indeed are the cause for the HICAS problems and when slowing down), you will

have to look at the speedometer (cluster)

 

Maybe someone installed a faulty mph converter or something..

Well I took the instrument binnacle cover off tonight to see behind the speedometer. I can see the KPH to MPH converter which looks to be connected firmly, they have spliced it into the yellow/blue wire in the speedo connector.

I tested for continuity between the yellow/green wire in the same speedo connector and pin 53 on the ECU and the connection was sound (disturbingly there were a couple of wires spliced into the yellow/green wire right next to the ECU. I don't know what they were for so I just removed them in case they were messing with the signal).

I checked with Conzult again and still no VHCL/S SE-MTR or VHCL SPEED signal - DAMN!!!!

 

Questions:

Do you know if I can check the voltage on this wire and what I should see?

I'm assuming the KPH/MPH converter must be working okay or the speedo would be wrong (speedo matches exactly with VHCL/S SE-A/T reading in MPH).

I'm guessing the next step is going to be a new instrument cluster?

 

So near yet so far :-(

It's a digital signal (0-5v square wave), so if you have a scope you should be able to see this waveform/signal on the Y/G wire.

 

you can try to remove the mph converter and see if it works then or try a different cluster

As Lymon suggested, remove the convertor and revert back to oem to test the cluster, you may have a faulty convertor

Well I'd never have believed it if I hadn't seen it with my own eyes!

 

I was reading through some old posts on other forums and came across someone describing exactly the same symptoms as I was seeing (can't find the post again now - sorry).

 

It had been suggested to them that some cheap USB Consult connectors were actually interfering with the cars signals and stopping the speed signals?

This sounded highly dubious to me but after thinking about it, I had always had the Conzult connected since the wiring breakthrough earlier in the week.

 

So I thought it was worth a shot and tried the car down the road last night without Conzult connected and..... Amazing, gear changes are perfect up and down and no HICAS light.

 

Excellent and thanks for all your advice guys.

 

I still have a lot of vibration, more so during hard acceleration and the transmission is very noisy and feels slippy and a bit blancmangey.

 

I'm going to check the drive shaft central doughnut mount and the gearbox mounts.

 

I have just ordered a new gearbox strainer and gasket (http://www.ebay.co.uk/itm/Transmission-Filter-Kit-Nissan-Infinity-1993-1997-RE4R03A-WCTK53-/141676923040) from Australia (!), which should be here by the end of the month, if someone could recommend the best ATF to use that would be really helpful.

 

I also thought I'd try some Lucas transmission slip repair fluid (http://www.ebay.co.uk/itm/Nissan-Transmission-Fix-Slip-Repair-Prevention-Premium-Lucas-Seal-/171694407785?pt=LH_DefaultDomain_3&fits=Car+Make%3ANissan&hash=item27f9c8c069) to see if that helps any, I'll keep you posted.

Still waiting for the gearbox strainer and gasket to arrive but I have now tried the Lucas transmission slip repair fluid.

I just added it to the existing oil as the bottle suggested, once the engine was at operating temperature.

It's an extremely thick red liquid that took ages to add through the dipstick tube.

 

The results appear slight, I'd say there's a marginal improvement in gearbox response.

 

I attempted a gearbox stall test today to try and determine where the whirring noise and vibration is coming from (I'm still getting very poor initial pull away torque).

 

I chocked all the wheels, applied the hand brake and the foot brake and then gently applied full throttle (within 5 seconds) to see where the rpms stopped rising in each gear.

 

The results were even across the board at about 2,700 rpm.

 

The WSM states the stall revolutions for a TT (RE4R03A) should be 2,950 - 3,200 rpm.

 

This puts me below the recommended. All I have read states that "Stall speed low in all positions" = Insufficient engine performance or faulty torque converter one-way clutch.

 

Would this explain the whirring, vibration and lack of torque?

 

I'm guessing the biggest clues will come when I remove the oil pan and strainer!

 

All thoughts appreciated.