autobox problem

[dannyboy77]

hi all bit of a problem with the old autobox. seems to be slipping gear after about 30mins continuous travelling may go form O/D to a lower gear for a bit then correct its self and go back to the gear it was in to begin with. if turn O/D off then problem seems to go away but has done it once in the last day or so.

bit of background the kickdown swtich is not wired in. its the lexus gearbox, the ECT isnt wired in, the magnetic speed sensor is working but the one on the TC is the surf speed sensor not the lexus sensor and giving a reading a 5th of the true speed on the combimeter.

any thoughts anyone?

[BUSHWHACKER]

Disconnect the transfer case sensor and see if it still does it.
Check the fluid level too.
Have you a transmission cooler fitted

On Lexurf III I didn't bother wiring up the ECT, Kickdown or O/D and it changed through all gears like normal including T/C lock-up @ 50mph.
It kicked down OK too!
It was an early 2nd gen Surf with a cable driven speedo though.

[dannyboy77]

was thinking along those lines about wondering if the signal from speed sensor 1 and 2 were conflicting the ECU and if the oil was loosing its viscosity (probably spelt wrong!) and fitting an oil cooler but wasnt sure if it was a mechanical issue as my mates mate is an autobox specialist so he is going to have an inital look but i wanted to see if you had come across this before