LS430 stuck in 3rd gear

tim hunter · March 12, 2018

I have an 03 LS430 with 153k on the clock. Driving home tonight it has decided it will no longer shift past 3 gear. The first 3 work perfectly, it just wont go any further - so 50mph is 3000 rpm.

A bit of googling found an old Youtube video of someone with the same issue, but no resolution or follow up.

Anybody here had this particular problem please?

Tim

ColinBarber · March 12, 2018

I'd firstly get the fluid level checked. If it is low that could explain the issue, but you then need to understand why the level is low.

The other possibility is a shift solenoid has failed, or is dirty/sticking.

steve2006 · March 13, 2018

Perhaps a diagnostic code read would help point you in the right direction. No warning lights on?

tim hunter · March 13, 2018

I plugged in my code reader this evening, and as suspected I have :

"P0751: Shift Solenoid "A" Performance or Stuck Off"

.. so its time to drop the pan and take a look. It is quite annoying that the code reports "A", but the workshop manual labels them 1,2,3,4 etc..

It appears a multi-meter would show 14 ohm for a good one and open-circuit on the bad one.

I hope its that simple and it can be coaxed back to life. They look pretty expensive and shipped from Japan or USA if I need a replacement.

Regards

Tim

tim hunter · March 16, 2018

A small update. The oil pan is off and the good news is that all solenoids test at 14 ohm, so that's encouraging. Oil is pretty black but not much obvious bits of metal in there...

Lexus want £85+VAT for new oil strainer, so old one currently soaking in the parts washer!

Just sourcing 4 litre of Toyota ATF Type T IV and then put it back together.

A couple of pics attached for amusement.

ColinBarber · March 16, 2018

That does look very dirty. I'd refill the pan, let it run for a bit and drain again to use up all of your 4l.

You have around 8l of fluid in the transmission, ideally you want most of that refreshed. I'd recommend you do three drain/refills in total over the next few weeks.

Malc1 · March 16, 2018

blimey, you're brave taking that lot to pieces

Malc

ColinBarber · March 16, 2018

I'd recommend you remove the solenoid and check it is working, using a 12v Battery and 10 W bulb in series. It is probably sticking or something is blocking it.

I'd expect a P0753 if the issue was electrical, which is confirmed by the coil resistance being good.

steve2006 · March 16, 2018

As Colin mentions I would also recommend the suspect solenoid is tested by applying power to it, the resistance may be correct suggesting the coil is intact but it is also a known problem that the plunger can become gummed up particularly as a result of old and contaminated fluid resulting in it failing to operate mechanically.

Malc1 · March 17, 2018

is the standard rule of thumb .....................don't do anything with the gearbox oil for the first 100k miles then every 36k miles thereafter to drain off two ltrs and refill ?

does that keep the oil in fair fettle for the life of the gearbox ( forever ? )

Malc

ColinBarber · March 17, 2018

7 hours ago, Malc1 said:

then every 36k miles thereafter to drain off two ltrs and refill ?

I'd probably go with every 20k miles, and I'd start at 100k or 10 years.

DaKa · March 19, 2018

Great Pics Tim and advice here - I didn't know about part replenishing the fluid 2 ltrs every so often, so will attend to that when I next DIY service.

I'm presuming that there is no special top up method, say as with Porsche, just pour in until it starts to flow out?

ColinBarber · March 20, 2018

On 19/03/2018 at 10:47 AM, DaKa said:

I'm presuming that there is no special top up method, say as with Porsche, just pour in until it starts to flow out?

No!

You drain the pan using the drain plug, and put back in the same amount through the dipstick tube. There is no level plug on the side.

You need to check the level using the dipstick markers whilst hot and the engine is running, having selected all the gear positions.

tim hunter · March 20, 2018

I have attached the actual filling instructions, from the Lexus manual.

There are dozens of posts on the web (mostly US Lexus sites) that discuss how/when/if the oil should be drained/flushed or whatever. My take on it all is that there are wildly varying opinions, mostly based on here say, concerning the best strategy to employ. My simple view (based solely on 40 years experience as a professional engineer and amateur car tinkerer) is that dirty oil with bits in is a very bad thing. How often you drain and fill or go to the effort of pumping it out and refilling till it is pink again - is pretty much up to you it seems.

Not got the thing back in one piece yet, but will report back when it gets done.

Tim

AUTOMATIC TRANSMISSION FLUID.pdf

ColinBarber · March 20, 2018

Make sure you use the correct procedure, and the correct fluid for your transmission. The procedure attached above I believe is for the 6-speed transmission fitted to the later LS430s which uses WS fluid. The older 5 speed need T-IV fluid and has a different procedure.

tim hunter · March 26, 2018

Hello again - well the good news is that it is all back in one piece and appears to work. This is the 6-speed, and the procedure I posted was followed. I had bought 4L of the T-IV - and when I did a check search for WS, the lists I saw show it as the same stuff. Anyway, most of it was consumed by the filling process so maybe the level was a bit low beforehand. All the solenoids were tested and clicked away merrily.

The bad news is that whilst under the car I spotted one of the rear arms was rather bent - no idea how or when. Whilst fixing that the rear level sensor on that side disintegrated and its sitting a bit low now! I have a replacement coming from Paul Frost so hope that does the trick.

Drove the car for 5 miles anyway, and the gears worked as they should, so when I get the suspension sorted I will know more.

ColinBarber · March 26, 2018

2 steps forward, 1 back. Hopefully everything will be good once you get the new sensor.

tim hunter · March 30, 2018

Well, it turned out I didn't need the new sensor - it was the cast ally link that had broken, probably due to the ball joint seizing up at the end. To get me back on the road I drilled, pinned and epoxied it back together and all is working again.

Just been out for a few miles cruising and can report 6 silky gears and a lovely floaty back end.

Hope this continues over the coming miles!

Tim