Intermittent Transmission Problem - 2005 Ls430

NeilP1960 · May 17, 2014

Had the car almost three years now, covering 60K miles - total mileage now 150K and have FSH, maintained via local independent Lexus specialist. Little costs to date other than regular servicing, tyres, O2 sensor and a wheel bearing - was running like a dream and always made me smile driving it.

Recently I've experienced a couple of problems - warning lights on the dash board *check VSC etc' have been diagnosed as a problem with the ABS pump/sensor a replacement unit is being sourced/costed as the fault codes can't be cleared apparently. Of more concern is an intermittent problem with the auto gearbox - the problem occurring more & more frequently. I was driving to Stansted airport a few weeks back when suddenly increased revs after being stuck in a two hour back log on the M6 - this didn't clear and I completed the journey at 4000 rpm and 50 mph - the car seemed to be stuck in 3/4 gear I suspect and wouldn't shift up (just down) with the manual/tiptronic option.

Parked up at the airport for a few days whilst I was away in Europe for 4 days and when I returned, the car ran perfectly for an hour when the problem returned and I completed the remainder of the 200 mile trip with high rpm's again.

I passed it to the local specialist for a couple of days and he reports that there are no fault codes showing up on the transmission and the car ran fine for him on 2x test drives. Just picked it up this morning and within 10 minutes, the problem returned. Clearly I'll pop it back to him this week for further investigation but would welcome any suggestions members might have, particularly if he informs me that there are no fault codes again?

Thanks

Neil

black400 · May 17, 2014

When in heavy traffic or at lights I always put the car in N , have you changed the Auto oil (ever), this might be the problem.

NeilP1960 · May 17, 2014

I've never changed the transmission oil but assumed it might have been done previously during the maintenance schedule, Will ask the garage to check/do regardless. Thanks for the tip re. heavy traffic and N position.

Titch LS · May 17, 2014

Neil, Ditto the gearbox fluid change. Make sure they use ONLY toyota type IV fluid. Nothing else.

NeilP1960 · May 17, 2014

Thanks Titch, much appreciated

ahmedali44 · May 17, 2014

Did they change filter or just oil??????auto boxes have filter in them it's worth changing that to @ might sort it. Or there is a electronic body inside box that might b faulty it happened to me in my e class many years ago.

jii · May 18, 2014

Mine (52 plate) had similar symptoms after only 70,000 miles due to contamination in the gear box fluid. Was told by a mechanically minded friend that this might be due to a previous replacement of radiator after a stone went through it - he said the two systems were apparently connected (seems odd to be but I ain't a mechanic).

Long story short I ignored it for a while and then needed a new gear box and torque convertor as it failed totally...

NeilP1960 · May 18, 2014

Thanks Justin

steve2006 · May 18, 2014

First thing to check is the transmission fluid,pull the dipstick and wipe it on some clean white kitchen tissue and see what colour it is, brown is bad, cherry red is good.

Next check is to smell the fluid if it smells burnt the bad news.

Although there is no set mileage/timescale it is thought to be a good idea to replace the transmission fluid every 60,000 miles.

Chances are the fluid will be bad which in turn can cause the shift solenoids within the transmission to gum up and stick, dependant on their position these solenoids make the gearbox shift up and down the gears hence why you have gear selection problems.

There is also a known problem with the transmission fluid intercooler on the LS430 which when it fails allows engine coolant to mix with the transmission fluid, there are no visible signs confirming this failure.

First thing is a full fluid change and then go from there if the problem doesn't go away.

As mentioned previously only use Toyota Type IV fluid.

black400 · May 18, 2014

Contamination could be a problem as the rad cools the gearbox , its the same on my subaru legacy

ahmedali44 · May 18, 2014

Its same as tx1 rad cools gearbox if rad leaks water mixes with oil @ then new box

NeilP1960 · May 18, 2014

Thanks guys, pointing towards the transmission fluid it seems, am I right in thinking that a problem here wouldn't result in a fault code too?

steve2006 · May 18, 2014

Won't always throw a code, the transmission ECU will only show a code if an electrical problem with the shift solenoids is detected,the fact that it sees this as being OK doesn't mean there isn't a mechanical fault with the solenoid i.e it doesn't move so no code will display.

black400 · May 18, 2014

Contamination could be a problem as the rad cools the gearbox , its the same on my subaru legacy

Titch LS · May 18, 2014

The gearbox 'filter' on the LS is actually quite a coarse strainer rather than a pure filter. It's 'only' there to keep out metal filings. It's no big deal if you don't change/clean it. It should last virtually forever as it will never clog up in the same way as an engine oil filter could. Also, on the 430 the correct anti-freeze is a must. I believe the corrosion of the radiator oil cooler (which allows water to mix with the gearbox fluid, thereby wrecking the gearbox), is caused by owners using the commonly found green/blue stuff which contains silicates. Toyota 'red' (premix) or the newer toyota 'pink' (already mixed) is the safe way to go. They are compatible with each other. That's what I would insist upon if I had a 430.

NeilP1960 · May 20, 2014

Update. Unable to check the transmission oil as the 2005 model doesn't have a dipstick as is 'sealed for life' - I believe this means 100K miles from what I've read in other places. I do believe there's a drain plug and fill point somewhere underneath though so have booked car into the independent to check and replace with fresh oil (Toyota WS) to see whether this helps. I've also sourced a reconditioned transmission just in case it doesn't.

bilmac · May 20, 2014

Thanks to all posters to this thread. My 430 is at 110500 miles, I assume it never had fluid change.

So for peace of mind, I will have it done now.

Also I will be sure to use only the recommended Toyota IV fluid, and red or pink anti freeze coolant. William

NeilP1960 · July 21, 2014

Update, got fed up with the local independent and went to Lexus Liverpool.... they did me a deal and cut their costs significantly and almost waived their labour costs, so new auto box, radiator, fluids and two new back boxes on the exhausts later... it's running like new... no regrets tbh

hihihi · July 21, 2014

Ouch, that sounds like substantial repairs were needed!

Would the problem have been contaminated auto box oil, ie when radiator coolant mixes into the oil?

I assume the exhaust silencers were a separate issue?

Malc · July 22, 2014

Blimey, sounds a nightmare costwise.

Malc

ahmedali44 · July 22, 2014

Omg must cost u a fortune

NeilP1960 · July 25, 2014

I suspect the oil was contaminated hence they recommended a new rad, the exhausts were a separate issue. I did ask whether they'd fit a recon gearbox and they would but at normal labour rates and wouldn't guarantee the unit clearly. In the end they did a new gearbox, torque converter, fluids and two exhausts and some (smart repairs on paintwork) for £4K including 15 hours labour and VAT - that's close to 45% discounted against the projected bill allegedly.. they gave me a courtesy car for a week too whilst they did the work.... it's the first real bill I've had in truth and I could put the cost through my business as it's my mode of transport... looks lovely and drives like a dream... fingers crossed! ;)