Thread: KZJ78 Transmission problems

A month or 2 back my 94 Landcruiser, KZJ78 started dropping down a gear as I was cruising on the seal, usually on an ever so gentle down slope. It wasnt overdrive, it was the normal gears. Might not happen for 50km's, might happen in 5km's. Very sporadic, and sometimes I might get 100 km's or more then it would do it several times. I turn the overdrive off for a minute or 2 travelling at about 3000rpm/100kph, then switch it back in to overdrive and it seems to go away until next time, or it could do this every 5 minutes for ages. Bloody frustrating.
Has been to mechanic 3 times, first time had the oil all drained, flushed, filters cleaned and new oil put in. Worked for about 100km. Second time the mechanic fitted a large as accessory oil cooler cos he said the original oil had been heated. I had towed a trailer a couple of times where the AT Temp light came on, so knocked it down a gear or 2 until it cooled down. Third time was last week and he replaced 3 wires in the loom that may have been shorting, possibly the sensor sender wires, who knows.
Went for a big arsed drive today and bugger me it still does it. totally random, no rhyme or reason when it will do it. Drove 50km, dropped down, did the old Overdrive off for a minute or 2 and it fixed it. Drove over another 100km and then it started at ti again.
Any one have any idea of where I start looking to find the fault?

Throttle position senso if it has one perhaps

Quite possibly the ECU, common on the KZN130 surfs to loose overdrive etc, there’s a guy in Nelson who was on to it fixing the ECUs use to just post them to him, can’t remember what he’s was called, might find him on google or trademe

Have changed ECU, no changes to trans, same, same. Its dropping down from top gear with the overdrive on, seems like its top gear, not overdrive.

No, couldn't be arsed. Don't say I notice any difference. Will gps both the Y61's at 2 grand and see if there's a difference. The shorty was a manual from the get go and the LWB was an auto. Will get back to ya.

our bog std terrano did something similar years back....scratching head I believe it was the switch on console that changes the way the auto decides to change...we used to call it american or european...one revs way higher before changing eg holds gear for longer ,the other changes at much lower revs.....
disconnected offending switch and havent had issue since...

That’s a diesel right?

My ‘96 series 80 developed symptoms like yours.

Similar numerous diagnostic interpretations

We ultimately traced it back to a failed injector pump.

Goes like a rocket now!!!!!!

Thanks guys, I've been taking all these ideas and passing them on to my mechanic. He's trying all the "simple" ones first cost he's reluctant to spend my money on anything major, in case it turns out it was a simple fix - I like that thinking. He is concerned with the state of the oil he took out of the sump, but tells me it was only burnt oil, no sludge or bits of "stuff" etc. And is now leaning towards it being more than a simple fix. The trans model is A343F.

Simple as mud! Are the 3 wires all in to the same plug thats on the side of the trans? This is sounding like I could actually do that.