LS430 rear air suspension sensors

[Ray Barratt]

My fab 2004 LS430 slowly looses air on the near side rear over about 4-5 days and an ex Toyota man suggests it could be this valve and possibly the metal pipe and it’s seals that link it to the air strut. Has anyone else have a suggestion. This valve is in very brittle shape but no air loss can be seen or heard. The next two images show normal ride height achieved in 30 -45 seconds of engine running.

[The-Acre]

The air system on the LS, or any luxury car, is so complex that diagnosing faults is very difficult, unless it's an obvious component failure like a leaking shock absorber.  Also, one part failing is very likely to lead to another due to age.  Having had three LS430's I know the most common suspension problems by far are strut leaks or height sensor issues.  If I was in that situation again I wouldn't hesitate in converting to conventional springs, that way your suspension woes are mostly behind you.  Most LS430's sold in the US were fitted with springs and people still loved the ride quality, just like the LS400.

[Ray Barratt]

3 minutes ago, The-Acre said:

The air system on the LS, or any luxury car, is so complex that diagnosing faults is very difficult, unless it's an obvious component failure like a leaking shock absorber.  Also, one part failing is very likely to lead to another due to age.  Having had three LS430's I know the most common suspension problems by far are strut leaks or height sensor issues.  If I was in that situation again I wouldn't hesitate in converting to conventional springs, that way your suspension woes are mostly behind you.  Most LS430's sold in the US were fitted with springs and people still loved the ride quality, just like the LS400.

I was hoping for a height sensor failure but my Toyota chum reckons the solenoid valve is very brittle being 18 year old plastic and even used appear to cost £200.00 and £400.00 new …. Ouch. I don’t understand why it looses its air on this side over a few days only as I would have thought that if the push in connectors are not seating correctly on one side why aren’t all of them failing ? Once running the ride is fine and the ride height can be changed via the dash switch. Grrrrrr springs to mind.

any further advice is greatly received 😁

[The-Acre]

15 hours ago, Ray Barratt said:

I was hoping for a height sensor failure but my Toyota chum reckons the solenoid valve is very brittle being 18 year old plastic and even used appear to cost £200.00 and £400.00 new …. Ouch. I don’t understand why it looses its air on this side over a few days only as I would have thought that if the push in connectors are not seating correctly on one side why aren’t all of them failing ? Once running the ride is fine and the ride height can be changed via the dash switch. Grrrrrr springs to mind.

any further advice is greatly received 😁

In my years of ownership I haven't heard of the valve leaking, there's a first time for everything of course. Maybe if you can get it up on a lift and spray the various connections with whatever the stuff the plumbers use to check for gas leaks is. 

[steve2006]

LDF....Leak Detection Fluid 😀

Screwfix sell it.

[Ray Barratt]

10 minutes ago, steve2006 said:

LDF....Leak Detection Fluid 😀

Screwfix sell it.

Blimey never thought of that …. Fantastic, I’ll post the results as soon as I track the issue down 😀

[Ray Barratt]

3 hours ago, The-Acre said:

In my years of ownership I haven't heard of the valve leaking, there's a first time for everything of course. Maybe if you can get it up on a lift and spray the various connections with whatever the stuff the plumbers use to check for gas leaks is. 

I see that another suggestion along the same lines has appeared too, so I will report back as soon as I have established what’s happening, brilliant 😁

[steve2006]

Here’s the stuff 😀

https://www.screwfix.com/p/flomasta-gas-leak-detector-spray-250ml/4520v?_requestid=199239#_=p

[Ray Barratt]

1 hour ago, steve2006 said:

Here’s the stuff 😀

https://www.screwfix.com/p/flomasta-gas-leak-detector-spray-250ml/4520v?_requestid=199239#_=p

Brilliant Steve, thank you. I have now read loads of stuff about the LS430 air suspension and my conclusions so far :

Air bag/struts hardly ever fail backed up by my ex Toyota engineer who looks after the vehicle for me and my son who is a Toyota service manager. Solenoid valve blocks may look like they are on their last legs but again don’t fail too regularly, and the less expensive front block cannot be used on the rear which also appears to have an arrangement of two inlets (for each side) and an electric plug connector, but presumably operate with different values. Often the height control switches fail due to muck and eventual normal wear and tear. I am still bemused however why the near side rear drops significantly over a 3-4 day period and as soon as it’s started raises in no time to it’s normal ride height. My curiosity keeps returning to a minor near side rear leak in the system that currently we cannot hear and no doubt this is where the magic LDS comes in 😁 plus replacing any of the frail push in connection bits (does anyone know if they are Voss).

don’t I go on a bit…. Yes but like most budding engineer types I like to understand how things work and when they don’t I need to understand what has contributed to its failure and what can be learnt to make it better for anyone else travelling the same highway.

Thanks Team Lexus Owners Cub afficenardo’s …….

[The-Acre]

Interesting read, although I dispute the suggestion that air struts hardly ever fail.  During my 10 years or so on this forum I've read many posts about strut failure, some simply going with a bang!  My previous car (now owned by Steve above) had two fail, one front and one rear, and that was before it reached 70k miles. 

[Ray Barratt]

1 hour ago, The-Acre said:

Interesting read, although I dispute the suggestion that air struts hardly ever fail.  During my 10 years or so on this forum I've read many posts about strut failure, some simply going with a bang!  My previous car (now owned by Steve above) had two fail, one front and one rear, and that was before it reached 70k miles. 

Thanks for your views Phil. My research into my slowly deflating near side rear is on a local/regional basis but of course the club extends Nationally and beyond and I always appreciate a response from those in the know. I look forward to liaising with my Toyota man next week to start diagnosing and report how we get on. Out of curiosity is their an independent specialist or club member closeish… to Milton Keynes should I get into difficulty 

[The-Acre]

10 minutes ago, Ray Barratt said:

Thanks for your views Phil. My research into my slowly deflating near side rear is on a local/regional basis but of course the club extends Nationally and beyond and I always appreciate a response from those in the know. I look forward to liaising with my Toyota man next week to start diagnosing and report how we get on. Out of curiosity is their an independent specialist or club member closeish… to Milton Keynes should I get into difficulty 

I don't know of one myself, but maybe someone will come along with some help. I'm even more curious than you are now to find the problem so keep us posted.  My money will be on a leaking strut but I never was much of a gambler!

Just as a thought. The air hose into the strut is surprisingly basic for such a complex system and is sealed with tiny o rings, it is possible it's leaking from there, hence the leak detector idea.

[Ray Barratt]

15 hours ago, The-Acre said:

I don't know of one myself, but maybe someone will come along with some help. I'm even more curious than you are now to find the problem so keep us posted.  My money will be on a leaking strut but I never was much of a gambler!

Just as a thought. The air hose into the strut is surprisingly basic for such a complex system and is sealed with tiny o rings, it is possible it's leaking from there, hence the leak detector idea.

Great idea Phil as my son has already got this hose ordered for me 👍 Great minds think alike and all that. Will post the results soon.

[Herbie]

Only just seen this topic so it may be too late but there's no need to buy leak detection fluid. Simply get an old jam jar or similar, put some water in and a squirt of washing up liquid, then use an old 1" paintbrush to apply the solution to any suspect areas. You'll soon see bubbles forming anywhere there's a leak.

[Ray Barratt]

On 5/1/2022 at 12:50 PM, Herbie said:

Only just seen this topic so it may be too late but there's no need to buy leak detection fluid. Simply get an old jam jar or similar, put some water in and a squirt of washing up liquid, then use an old 1" paintbrush to apply the solution to any suspect areas. You'll soon see bubbles forming anywhere there's a leak.

Thanks Herb. My technician says he used the soapy water route which has lead him to suspect the rear solenoid block which we believe to be Valve Number 2 in Lexus parlance 48096-500400. Interesting thing is the simple fact at the same time that this near side rear slowly deflating issue began the vehicle Battery would not keep its charge, almost as if it had a parasitic drain going on. To be on the safe side I bought a new Battery which stopped any issues for a few weeks and then the Battery would drain out over a week or so if not started. Does anyone think that the slowly deflating near side rear and the parasitic Battery drain are connected in some way as the Number 2 solenoid block has both air and electric connections or am I reading to much into it ? Just a thought from a newbie 😁

[steve2006]

Easy enough to confirm, get your mechanic to measure the parasitic current drain then disconnect the solenoid electrical connection and measure it again.

My Battery was completely flat after being stood 3 weeks at the airport recently.

[Ray Barratt]

5 hours ago, steve2006 said:

Easy enough to confirm, get your mechanic to measure the parasitic current drain then disconnect the solenoid electrical connection and measure it again.

My battery was completely flat after being stood 3 weeks at the airport recently.

Thanks Steve 😁 I will make all the findings and results good and not so good in due course 👍

[Ray Barratt]

On 5/3/2022 at 11:50 AM, Ray Barratt said:

Thanks Herb. My technician says he used the soapy water route which has lead him to suspect the rear solenoid block which we believe to be Valve Number 2 in Lexus parlance 48096-500400. Interesting thing is the simple fact at the same time that this near side rear slowly deflating issue began the vehicle battery would not keep its charge, almost as if it had a parasitic drain going on. To be on the safe side I bought a new battery which stopped any issues for a few weeks and then the battery would drain out over a week or so if not started. Does anyone think that the slowly deflating near side rear and the parasitic battery drain are connected in some way as the Number 2 solenoid block has both air and electric connections or am I reading to much into it ? Just a thought from a newbie 😁

 

[Ray Barratt]

Just now, Ray Barratt said:

 

Well team Lexus with particular thanks to Herb, Phil and Steve I can now report that my near side rear LS430 slowly leaking air suspension has been sorted by my good friend Jimmy Martin at Auto Tec Studio Salford in Beds which is actually in MK. He is ex Honda and Toyota and really knows his stuff and fitted a near side rear air suspension pipe (looks very flimsy to me) plus the most important bit the rear isolation valve 48096 50040 which I found in Japan new at Amayama for £125.00 + shipping compared to over £400 and a 4-6 week lead time from Lexus UK. Car now fully sorted but the parasitic Battery drain remains 😩

[Ray Barratt]

24 minutes ago, Ray Barratt said:

Well team Lexus with particular thanks to Herb, Phil and Steve I can now report that my near side rear LS430 slowly leaking air suspension has been sorted by my good friend Jimmy Martin at Auto Tec Studio Salford in Beds which is actually in MK. He is ex Honda and Toyota and really knows his stuff and fitted a near side rear air suspension pipe (looks very flimsy to me) plus the most important bit the rear isolation valve 48096 50040 which I found in Japan new at Amayama for £125.00 + shipping compared to over £400 and a 4-6 week lead time from Lexus UK. Car now fully sorted but the parasitic battery drain remains 😩

 

[steve2006]

That’s a great result there Ray especially finding a decent independent and making a fantastic saving on parts as well as expedited delivery.

Also thank you for your comprehensive report after repair this always proves useful to other members in similar positions.

Just the Battery drain to sort then, could the same guy not look into this also?

I’m also going to move this post into the LS section.

[Ray Barratt]

1 hour ago, steve2006 said:

That’s a great result there Ray especially finding a decent independent and making a fantastic saving on parts as well as expedited delivery.

Also thank you for your comprehensive report after repair this always proves useful to other members in similar positions.

Just the battery drain to sort then, could the same guy not look into this also?

I’m also going to move this post into the LS section.

Thanks Steve. I hope to be a contributor where I can. I have the Amayama exploded diagram I used to order the part which I can also attach if you think it would help. My technician is on honeymoon for a few weeks and I will report how we get on with the parasitic Battery drain in due course and can also attach his website details should other members need his services 😁

[steve2006]

By all means post up the diagram and your service guy details, one of the most asked questions on the forums is “Anyone know of a good independent in “ 

[Ray Barratt]

On 6/7/2022 at 4:15 PM, steve2006 said:

By all means post up the diagram and your service guy details, one of the most asked questions on the forums is “Anyone know of a good independent in “ 

[Ray Barratt]

Just now, Ray Barratt said:

This is the parts diagram I used from Amayama to get exactly what I needed in a matter of days directly from Japan in original Toyota/Lexus packaging. My technician wizard is Jimmy Martin from Auto Tech Studio Wavendon Road Salford Beds 01908 587543 and knows these cars well. Going to get to the bottom of the parasitic Battery drain over the next few week, hopefully 😁

 

1 minute ago, Ray Barratt said: