# Sensor underneath motorhome - anyone know what it is?



## jonandjules (Jun 21, 2009)

I have recently noticed this sensor under the rear of my Hymer S820 motorhome. Anyone know what it is for?


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## SaddleTramp (Feb 15, 2007)

Does it have air suspension, If it does it looks like a leveler

it senses when turning corners and axle lifts on opposite side so more pressure is pumped in other.


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## jonandjules (Jun 21, 2009)

Thanks for the reply. No, it does not have air suspension.....it definately looks as though it is measuring the distance between the ground and the motorhome.

The motorhome is a Hymer S820. I also wondered if it was maybe a warning device if towing with too much weight? Or how about a sensor to do with a tracking system?


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## steco1958 (Mar 5, 2009)

JohnandJules,

I would try and follow the cable that comes out of the unit and is secured to your chassis.

It may give you an indication

Steve


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## GEMMY (Jun 19, 2006)

I think you'll find that it is a remote external temperature sensor.

tony


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## Carl_n_Flo (May 10, 2005)

Were you not told???? Of course not!!!

It belongs to GCHQ and is the prototype device for the Government to keep track of your whereabouts and speed at all times....

Sensors in the road surface collect the data and pass it on...

You are the first in the UK to try it.....and now you have found it...

Methinks the 'MIB' from GCHQ will be round later to deal with you...

8) 8) 8) 8)


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## DaveJM (Dec 29, 2008)

I looked under my 820 today and could not find a similar sensor. 

I do know however that the external temperature sensor is located underneath close to the steps - only a small tube about an inch long and 1/4 in in diameter.

Mine doesn't have any additional levelling devices nor has the suspension been altered in any way. It is the 616 chassis and a 2002 model.

Just a thought could it be something connected to an alarm?

Good luck and do let us know when you solve the mystery.


David


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## pippin (Nov 15, 2007)

You will need to ask 007, M, or Q.


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## wackywyco (Apr 30, 2007)

Dunno,but have you considered the Bomb Squad! :lol:


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## jonandjules (Jun 21, 2009)

Thanks for the replies - I tried tracing the wire but it just goes onto a junction box.

It's definately not a temp probe.

The way it points down makes me think it is 'looking' at the ground......strange???


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## MADMICK1945 (Mar 10, 2010)

This vehicle is reversing??


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## jonandjules (Jun 21, 2009)

It can reverse...............


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## pippin (Nov 15, 2007)

Perhaps - but can it go backwards?


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## Spooky_b329 (Jan 24, 2009)

Unplug it, then see what doesn't work! What is the base chassis?


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## Spacerunner (Mar 18, 2006)

Trembler switch for an alarm system?


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## pippin (Nov 15, 2007)

_Trembler switch for an alarm system?_

Test by having a knee-trembler and see if it goes off at a certain moment?


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## bigfoot (May 16, 2005)

Its an MGT chip (musical good taste) whenever you put a Daniel O'Donnell or Barry Manilow CD in the player it switches it off until you put in Led Zep or Queen!!!!


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## jonandjules (Jun 21, 2009)

Spooky_b329 said:


> Unplug it, then see what doesn't work! What is the base chassis?


It's a Mec 616 (2004).

I just might try unplugging....


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## tramp (May 25, 2005)

if its linked to the rear brakes? it will be the load sensing device which when the weight over the rear axel increases the pressure to the brakes is changed to prevent rear whell lock up aka Arctic lorry smoke off back wheels :lol: :lol: .

The temp sensors are so small you prob miss them [about 1cm long] and small wire].


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## JeanLuc (Jan 13, 2007)

Is this unit attached to the main 616 chassis, or the chassis extensions at the back that carry the garage etc? If it is on the extensions, it is unlikely to be anything to do with the base vehicle. Perhaps linked to some Alko device? If the S820 has electric steadies at the back, there should be a warning sensor to tell you if they are down when the engine is started. Is it anywhere near the steadies?
The 616 has an air-brake for parking. If the blue device is on the main chassis, is it anywhere near the rear axle / wheels? If so, it might be linked the parking brake, although I cannot see what its function might be.
Other than that, I haven't a clue but would suspect something to do with an alarm or tracking system.

Philip


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## jonandjules (Jun 21, 2009)

Still can't figure this sensor out........I have rear steadies fitted (though I don't use them), tried them and there is no alarm.

Tried unplugging it and the police turned up............no, not really!


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