Cant get auto transmission in 89 GQ auto to go into diagnostic mode.

[NissanGQ4.2]

But I still cant figure out why, before he touched it, the problem was the converter wasnt locking up, after he did the converter, cant get into diagnostic mode, so from the time i dropped it off to the time it got back to me, something happened to stop it from going into diag mode... he said if it was his car he wouldnt worry about it, i said its not your car its mine and i am worried about it...

It may be the case that the diagnostic mode is still working but is giving you a different error to the one you had before it went in for repair.

Without actually seeing you do the test I cant say for certain that it is or isn't going into diagnostic mode, from what you have said it sounds like it is still going into DM and giving you an error

[ckh]

resolved lock up flaring but replacing the speed sensor

[Alitis007]

I bet you feel like a massive weight had been lifted from your shoulders!! NOW GO OUT AND ENJOY!!!!

[taslucas]

resolved lock up flaring but replacing the speed sensor

Awesome to hear mate. I suggested it in post number 23 in this thread and i think even earlier in one of your other threads lol, 70 odd posts later its resolved. Now sit back and enjoy the superior properties of driving offroad with an auto
It took me $4200 to get rid of my problem (and still dont know how/why it went) but i got the Nomad heavy duty valvebody fitted during that time too. So your headache was a bit cheaper

Ill say again: GREAT STUFF MATE! THE HEADACHES ARE OVER!

and as Alitis said: GO OUT AND ENJOY!!!!!!!!!!!!!!!!!!!!!!!!!

[ckh]

resolved lock up flaring but replacing the speed sensor

had to go for a long drive to do a job today, after about 20min driving the flaring is back... but not as bad..

[NissanGQ4.2]

Very interesting indeed

Am also interested in the "330 ohm resistor trick" to fool the tcu into thinking its at the correct temp.

Don't recall reading or hearing anyone do that before

[ckh]

Very interesting indeed

Am also interested in the "330 ohm resistor trick" to fool the tcu into thinking its at the correct temp.

Don't recall reading or hearing anyone do that before

Found it on another forum...Took a measurement of the temp sensor loom resistance and it wasn't good (reading open circuit). Either way, I preceed with the plan & measured the voltage across pin 12 of the TCM (PURPLE WIRE). At first the reading were normal ie 1.56v when cold. I took the car for drive whilst monitoring the multimeter & could see the voltage dropping as the box warmed up (all normal). However, not long after the voltage went from .96v straight to 2.57v & the problem occurred ie no 4th gear. I toggled the battery isolation switch as I've done many times in the past and the voltage went back down to .95v - welcome back 4th gear. Seems the temp sensor was going o/c intermittently confusing the TCM.
I've added some photos of what I've done to by-pass the issue so others can avoid the expense (TPS & Revolution sensor which I've done in vain) & over-all trouble.

1) You'll need to get yourself a 330ohm resistor ( I went with a 1watt which I think is overkill) but for 45cents you get enough to do your truck & a mates!


2) On my GQ the terminal block which houses most if not all the wiring for the transmission & is the 'BROWN CONNECTOR' which is in the middle (see pic).


3) Once you've disconnected the terminal you need to find the 'BLACK & WHITE' wire both of which are smack bang in the middle. I cut both with a little extra length then soldered the resistor & little wire in a loop back to the wires which were previously cut. To finish, I added some heat shrink to protect the resistor & to make it look tidy.


4) Once done, reconnnect the all wiring & verify your work by measuring across pin 12 of the TCM & ground (ignition on). If you get .46v (or there abouts) you've got 2 thumbs up!!!


By installing the resistor you negate the need to drop all your tranny fluid, remove the pan & most important spend a squillion dollars at nissan. All the resistor does is make the tranny believe it's hot/ warm from the get go. So keep it in mind and try avoid getting to speeds which will 'lock the torque converter' before it's had enough time to warm up.