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New Member
Dec 2, 2020
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Hi Forum,

Have a 100 Series Sahara Diesel which will not change from 4th to 5th / lockup. When the problem first started cleaned the speed control sensors and wiring plugs on transmission and worked again for a few moths until problem reoccurred. Changed speed control sensors and plugs from working transmission and no change. Toyota plugged in their diagnostic computer and everything checks out OK. Transmission Oil and filter was changed in January before problem started at 305,000 km.

Hopefully someone can point us in the right direction with this problem.

You have not said what year it is and what is the oil level on the gearbox dipstick?
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Hi Steve, 2009 model and oil levels are spot on, double checked after short run when oil is not at max temp and all OK.
A 2009 HDJ100? Should that read 1999? When I first got an automatic, I checked level and read the owner's manual at least 5 times before I realised that it has to be done with the engine running... Then added another litre of atf.
My 2000 100series auto is a 4 speed box are you sure you have 5??
Sorry guys that was a stupid typo, it's a 2003 model, engine number 1HD-0236819
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Well what do you call the next shift that happens after changing from 4th. In 4th at 100 kmh the revs are sitting around 2800 rpm, after shifting to 5th the revs are around 1700 rpm when it was shifting.
I am not conversent with that box as mine is a 2004(facelift) and it has five gears, but I think I read that the four speed had a "lockup" which you mention, take a picture of the gear shift lever and post it on here and we will be able to tell off that
Also a Five speed does not have a dipstick (on the gearbox) as it is classed as sealed for life
It can be a 2003 and 5 speed. On LC100 it's easy: the 5-sp has a gated shifter; the 4-sp has a straight shifter movement and a O/D Off button on the stick. Quite a few other changes came at the same time, in engine, engine-ecu, instruments, dash, SRS, etc.
And, btw, the first year of the 5-speed box had a dipstick.
What you call the shift in 4th gear (or 4th and 5th if it's a 5-sp) is "Lock up". That's when the converter locks the incoming to the outgoing shaft, which happens only at normal operating temperature (not when cold), and only at over 60 km/h, and only when you don't ask for too much power.
I had a similar problem on my 2004 5 speed 100 a few years ago, it suddenly stopped locking up, there were no warning signs and I didn’t have the intermittent fault you’ve had. I eventually found that there are two temp sensors in the auto box, one feeds the transmission temp warning light, the other prevents lock up until the fluid reaches a preset temp as Uhu has said and that had failed.
If you do have the 5speed, the sensors are an integral part of the loom inside the box, the other connections are for the solenoids.
Once you drop the pan it’s an easy job to change, it feeds in from where the multi plug fits on the side of the box and you’ll also be able to clean the filter while you’re at it.
The filler plug is tucked away on the opposite side of the box to the multi plug, it is NOT a level plug, however there’s plenty of info on how to fill to the correct level, the plug will probably have WS stamped on it in which case you will need the correct Toyota WS atf.
If you’re going to do this yourself, be careful when you release the pan as there is still plenty of atf in there once you have emptied it via the drain plug!
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Good day Steve, uHu and Geoff , thanks for your responses and clarification on my problems. This forum is really well set up and is full of seriously knowledgeable and enthusiastic Landcruiser owners. We have managed to solve the problem by cleaning all the plugs / connector boxes on the harness from the transmission to the ECU unit. We did find some corroded terminals which would not have made good connections. Thanks for clearing up whether this is a 4 or 5 speed transmission. As suggested this must be a 4 speed with "lockup". I would like to comment that the lockup drops the revs by around 1000 rpm at 100 km/h which feels like a 5th. What is strange is that the lockup has two quick changes, the first dropping 800 rpm and straight afterwards dropping a further 200 rpm. Any comments on this.

Another question for the team. There is snatching in the transmission sometimes pulling off quickly in 1st or pulling off on a steep incline . Also there is snatching sometimes in changing down and accelerating after going around a traffic circle. This has started recently while the transmission was not changing from 4th and is still doing it. Is this another electrical gremlin.
Good to hear you have solved at least one of your problems, Hopefully someone on here will be able to help you with the transmission snatch.