TB42 Auto box Electricals?

[taslucas]

Hi, as some of may know i have been having issues with the lock out torque converter. It engages and disengages rapidly on the highway.

First i had a reco torque converter fitted, then a brand new Throttle position sensor.
This has been done by an auto specialist who has checked over the system.
Still got the same problem.
The mechanic now has the box apart and says its in really good condition, says it looks like it has recently been rebuilt. (ive not long had the patrol)

Mechanic now thinks it may be electrical: ECU or Road speed sensor.

Firstly, does anyone have any ideas?
And secondly how big a job is it to remove the dash and change the road speed sensor?
How much should a road speed sensor and ECU cost?

Missed out on having the trol on the road for the xmas break
Havent driven it much in the last 3 months!!!! Going CRAZY!!!

Thanks for any help

[jc58nc]

Does it drop out of lock on flat highway ? Or just when you hit a hill ? (Normal)
I have a 4.2 auto so I can compare yours to mine for you.
I used to have a Commodore ute auto that would drop back to third gear on the Hume Highway going to Melbourne while sitting on 110kms, that was normal

[taslucas]

Nah its on a flat highway. Definately not just normal kickback. It goes in out in out in out in out in out about as fast as youre reading that! and continues to do it until i either back right off and slow down (below 90 k's) or press the foot down and make it kick back properly.

[Bigrig]

Lock up solenoid???

[taslucas]

Lock up solenoid???

Cool thanks thats another to check.

[Bigrig]

Cool thanks thats another to check.

Sounds a bit odd, so what was said about the engine speed sensor? Also, like me, have you changed the coil lately by any slim chance?? Tachometer steady and not bouncy at all anywhere through the range?? You said you ruled out the TPS so that is about all I have based on the issues I've been having also ...

Good luck!!

[gq4200]

If you had another Instrument Cluster you could try and swap this.
The other thing I would do if you have some electrical know how would be to cut the wire from the Auto ECU to the Torque Converter Clutch (Lock - up) Solenoid. Pin 22 on the ECU. If you download the GQ Service manual in the downloads it is on page 469 (AT-62)... Looks like a Grey/Red wire if you look at the next diagram. This wire is the output from the ECU and turns on the Solenoid inside the Transmission to Lock the Converter. Once the wire is cut you can connect it to +12v whenever you want the Trans to Lock. Anything Over 80 km/h would be fine. This will tell you if the Transmission is faulty or the ECU is telling the Solenoid to turn off/on.
Another option would be to measure the voltage / connect a small lamp to this wire and watch what the ECU is commanding the transmission to do.

[NissanGQ4.2]

Hi mate, Is it the original valve body?

[gq4200]

I would also check the switch on the Transmission Lever. Have a play with the switch while it is locking/unlocking. This switch will lock/unlock the converter at speeds of over 95km/h.

[taslucas]

Hi mate, Is it the original valve body?

the gearbox was replaced about 4 years ago (got receipts with the vehicle). The box is out of the vehicle and in pieces atm, i called in and saw it this afternoon. My mechanic said that it has been rebuilt recently and so was looking very good inside (although the vehicle did not come with any receipts for this) Not sure if the valve body is the original one but it is standard. The gearbox is in great condition (the mechanic has just pulled it down and cleaned every little bit!) so that cant be the problem, The TPS is brand new so that cant be the problem, The torque converter is a reco one and only been fitted for about 500kms, All the fluid lines etc have been checked. So we are thinking it must be an electrical problem ie; speed sensor, ECU, or as Bigrig said maybe the lockout solenoid...... or something else.
Was thinking maybe get another ecu and swap to test?