2017 SR5 load assist airbags

2017 SR5 load assist airbags

Postby Mattlucasv on Sun, 09 Jan 2022 6:23 +0000

Hi All

Whilst I understand they may not be the best thing we recently fitted some rear load assist airbags to help level out the car and camper trailer when towing. We don’t really want to upgrade the suspension at this time and these are a bit of a interim solution until we start traveling more.

But this got me thinking and I’ve tried looking under the car (could be hidden but I can’t see anything) and then online but can’t really find any confirmation and seems to depend on if you have VSC etc, does the 2017 SR5 have a load sensor/proportioning valve that directs more breaking pressure towards the rear breaks when under load?

Just wondering if it does how would it work when the camper trailer is hooked up and pressure in the airbags to level everything out? I would think given the car is “raised” it would think there is no load so the front breaks would be doing the majority of the breaking?

If this is the case are you able to adjust it so the correct amount of breaking pressure is directed to the rear breaks so the front breaks aren’t working as hard?

If this isn’t the case and there isn’t a load sensor then I’ll move on and stop “worrying” about it for our next trip!
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Re: 2017 SR5 load assist airbags

Postby Gipsy on Sun, 09 Jan 2022 7:27 +0000

All I can say is if you need airbags then you're overloading the Hilux! Load-leveling bars should even out the load between the trailer and the Hilux. If they don't, then something is overloaded. I tow 2.5 tonne behind my Hilux and the load-leveling bars are sufficient to equalise the load between the Hilux and the caravan even with 230kg tow ball weight. Airbags have a known history of cracking chassis and I expect it's because they encourage overloading and the vehicle is not designed to have them.
The brakes issue is also part of the whole scheme of things... You must have electric brakes adjusted to equalise the amount of braking between the vehicle and the trailer. One way to check this is to put your Hilux and trailer, fully loaded onto a weighbridge and you might be surprised how much your combination is overloaded. This can also demonstrate the weight distribution between the vehicles. If you don't do this, somewhere down the road the transport authority will do it for you and you won't enjoy the outcome if you're overloaded.
As to brake proportioning valve I understand all vehicles have them but as you suggest, airbags spoil the whole issue. If your vehicle/trailer combination is correctly loaded, the proportioning valve will be set at the appropriate level.

Hope this helps ;)
Last edited by Gipsy on Sun, 09 Jan 2022 7:57 +0000, edited 1 time in total.
Cheers Gipsy :D
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Re: 2017 SR5 load assist airbags

Postby Gipsy on Sun, 09 Jan 2022 7:42 +0000

I know you're is gen8 but this may help you understand

viewtopic.php?t=15237
Cheers Gipsy :D
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Re: 2017 SR5 load assist airbags

Postby Mattlucasv on Sun, 09 Jan 2022 8:19 +0000

Thanks for the reply, I don't think we're overloading it to be honest its just a standard camper trailer 1.5 tonne with an ATM of 1.9 tonne, fully packed up ready to go its more likely to be around the 1.8 tonne I would think, generally we travel with water tanks etc empty and fill up before getting to where we're going so we're not having to drag around all the extra weight and like I say its more just to help "level" it all out when towing as it does sag a bit. For the break controller I generally have it set to the point just where the camper trailer doesn't feel like an anchor dragging behind the car when breaking. But like you say it's probably worth double checking it and getting wieghts checked!

Looking at that thread/topic I don't see anything like that connected to the diff and chassis that would work as a LPV, I've also tried looking at various workshop manuals as well and nothing mentions one hence my confusion if it as one or not :?
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Re: 2017 SR5 load assist airbags

Postby Bushwalker8 on Sun, 09 Jan 2022 10:04 +0000

Don't get distracted with old school LSPV, to answer your specific question Gen 8 doesn't have it.

The electronic systems such as VSC & TSC look at a multitude of other sensors - including monitoring each wheels speed and acceleration, and brake each wheel individually to suit. If you look back underneath you will see two separate brake lines all the way back to the axle separating out one to either side. So a single dinosaur mechanical valve isn't exactly going to help.

The Gen 8 braking sensor list and monitored parameters include things like yaw rate, steering angle, lateral G, master cylinder pressure, deceleration, accelerator angle etc. There's nothing listed related to load, height or pitch so there doesn't appear to be anything hidden somewhere else.

The only height sensing I'm aware of is on SR5 left spring rear for auto headlight adjustment.
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Re: 2017 SR5 load assist airbags

Postby Gipsy on Sun, 09 Jan 2022 12:49 +0000

True bushwalker vsc,TSC, abs and other systems combine to do the job but ultimately it's all about brake control, it's just electronics in a 'black box' and not a physical valve doing the job. Maybe even the headlight adjustment sensor plays a part in it.

Matt, don't forget to add up all the stuff you have in the tub and the cabin. I suggest you take it all to the weighbridge next time you're packed for your next adventure ;) And don't forget the family... So many vehicles are loaded to the max before anyone gets into their seats. It's all counted in the gcm (gross combined mass) of the rig, including the occupants and fuel in the tank!
Cheers Gipsy :D
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Re: 2017 SR5 load assist airbags

Postby Bushwalker8 on Sun, 09 Jan 2022 5:54 +0000

Gipsy wrote:Maybe even the headlight adjustment sensor plays a part in it.

No it doesn't, it's not included on the braking sensor list. And it's not on SR and the VSC & TSC are the same SR & SR5.
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Re: 2017 SR5 load assist airbags

Postby Gipsy on Mon, 10 Jan 2022 5:27 +0000

I did say 'maybe' but unless you are a highly paid Toyota electronic specialist we are all having a guess aren't we? ;) It is all electronic wizardry and not many here on newhilux would be insiders with the complete and complex knowledge.
Cheers Gipsy :D
My 2013 auto D4D DC SR5, prefilter, 3" exhaust and Chip with egt probe, stock SR5 rims with Toyo Open Country AT2 265/65R/17's
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Re: 2017 SR5 load assist airbags

Postby Bushwalker8 on Mon, 10 Jan 2022 11:23 +0000

Gipsy wrote:unless you are a highly paid Toyota electronic specialist we are all having a guess aren't we? ;)


Sorry, wrong again. The technical information is available from Toyota. And a lot of it has also been previously shared on this forum which is where I first obtained it. Maybe do some homework before jumping to incorrect conclusions & posting them.
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Re: 2017 SR5 load assist airbags

Postby Gipsy on Mon, 10 Jan 2022 12:22 +0000

Must be really good to be always right... So you're a highly paid Toyota electronic engineer then??
Oh yes I need to do some homework... Sorry teacher I must do better in future... And your qualifications?? Social media expert it seems...
Cheers Gipsy :D
My 2013 auto D4D DC SR5, prefilter, 3" exhaust and Chip with egt probe, stock SR5 rims with Toyo Open Country AT2 265/65R/17's
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Re: 2017 SR5 load assist airbags

Postby Bushwalker8 on Mon, 10 Jan 2022 1:23 +0000

Gipsy wrote:a highly paid Toyota electronic engineer then??.......Social media expert it seems...

Ummm, neither.....but I can read. If you aren't able to find it in this forum everything is detailed here if you look: https://toyotamanuals.com.au/document/l ... 15-current
I'm sure even you could do it if you tried hard :roll:
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Re: 2017 SR5 load assist airbags

Postby hiluxxury on Mon, 10 Jan 2022 5:04 +0000

Mod note: please keep discussion civil or risk being banned.
I might be wrong.

2005 SR Hilux 1KD
2012 Range Rover Sport SDV6
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Re: 2017 SR5 load assist airbags

Postby dave g on Mon, 10 Jan 2022 7:57 +0000

[quote][/quote]
understand they may not be the best thing we recently fitted some rear load assist airbags to help level out the car and camper trailer when towing. We don’t really want to upgrade the suspension at this time and these are a bit of a interim solution until we start traveling more

Don't use the airbags to lift just put in the minimum amount of air for the best result they are meant to be a helper not a solution this is how I have used them for the last 27 years and never had a problem
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