Lexus GS450h Rear height sensor disassembled...

[Cavanman01]

Hello Folks,

I just thought I would post some images of a rear height sensor that I just disassembled today. I was curious to find out where it was seized and how it worked...

A couple of months ago my car failed it's NCT (National Car Test, equivalent of an MOT) for poor headlight adjustment. It turned out that the rear height sensor had seized, in a bad position, which caused the headlight aim to be too high. I have attached a photo of the old sensor, as taken off the car. You can see that in fact the sensor had seized so badly, it fatigued the mounting bracket and broken it away. Everything was retained just by the connecting wire.

I bought the replacement on the following website. The part included the bracket and connecting strut, so maybe the mounting fracturing is a common occurrence... It was €108 + €32 delivery, which seemed reasonable at the time. The part fitted straight in and worked with no issues. 

https://www.miessler-automotive.com/LEXUS-GS30-35-43-460-GRS19URS190UZS190-Level-sensor-89408-30130-rear-left

I've attached some other images, which provide some additional detail, hopefully they are high enough resolution. 

You can see on the "Sensor Side View" image the upper part of the sensor where the connecting arm is attached. It would appear that the shaft is sealed with a conventional, small oil seal, complete with spiral inner spring. Unfortunately the seal did not survive the disassembly process. 

The rust and corrosion were confined to this upper area. Once I had cut around the housing, to release the seal, the sensor could turn, albeit stiffly. However it felt correct and I would say would continue to have worked. 

I disassembled further, as you can see. I had been expecting a resistance type sensor with a carbon track and a wiper. However it appears to be magnetically based in some manner. The "rotor" appears to have 6 slots but only 4 have magnets. The housing has a protrusion that the rotor sits over. I don't know the principle it uses; perhaps some of the electronically-savvy member may be able to shed some light. 

Regarding the car itself, that is heading for the great scrap heap in the sky (or where ever I can get the best scrap price). To cut a long story short, the rear subframe has corroded to such an extent that lower arm, which runs forward to the subframe on the right hand side, has broken clean away... The car actually drives OK, but having heard a heavy clunk, I investigated and found the mounting broken away. 

I was disappointed in myself not to have spotted this before, but to be honest, it never crossed my mind that a substantial rear subframe on a (relatively, '06) modern car could rot to that extent... In fact I'd changed the wheel bearing twice on that side and never thought to check. 

However I've run out of patience with the car; a replacement hybrid Battery last year, 3 rear wheel bearings in the last year, the gearbox hydraulic pump just after Christmas, the rear disk shields rotted away. I had actually bought a new front wheel bearing as well, as one of them was noisy, but never got to fit it...

All in all, the hybrid experience has been interesting and I think the tech in these cars is second to none. But now I think it's time to go back to something more conventional.

Happy motoring,

Cavan Man