Volvo XC 70 Seats into a Vito 639

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m80

MB Enthusiast
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Apr 26, 2015
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Location
Derbyshire, High Peak
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Viano ex long, 651 2014. S211 646 2009 (till the Gov't drones blow 'em off the road)
Having read that Volvo seats are comfortable I'm attempting the change over.
Power to the motors and the heating isn't over complicated and I believe I've worked that out.

My issue is working out the occupance sensor. On the Vito I'm ok with the +ve, -ve and data wires, but as expected the Volvo wiring is different. On the replacement seats there are 2 wires instead of three as in 'orange' and 'blue / orange'.

I would be surprised if anyone here could help with the Volvo style of things but if I could understand what sort of signal is expected on the Vito's data wire it might help me find a work around.
 
I recently fitted a set of Impreza STi seats to my Forester and did a bit of general retrofit Googling before I carried out the work.

20190906_174145[1] by Kenny Niven, on Flickr

Some occupancy sensors are a type of weigh scale to alter the deployment force of the airbag , the Volvo may just have one setting (two wires) as opposed to possibly two settings (three wires) on the Merc seats.

Cant you put a MM on the sensor connections of the Merc seats and try different weights on the seat and compare readings , then see what the Volvo seats are reading with a weight on them.

Is the occ sensor removable / transferable from one seat to another as it may just be a flat pad and can be easily moved , that way it will keep the car electronics happy.

You could also get a resistance value from the Merc sensor with it occupied and then fit a resistor to the underseat plug (car side).

The Subaru ones were quite straight forward , seat belt clips swapped over to keep the wiring simple / airbag connections were the same / no occupancy sensors on either original front seats. The only PITA were the mounting brackets which took many attempts to get them fitting properly as the Forester floor was nothing like the Impreza floor due to a nine year age difference.

K
 
Aye, I spent till the early hours looking for volvo wiring diagrams, nothing so far.

I'll try connecting 12+ve to the Volvo 'orange' and see what returns on the other wire. Thinking that the Vito 'Data' wire maybe a canbus return to a controller I don't want to send significant voltage into it.

These seats need raising 12mm due to an underslung motor. I'm aiming to mount onto rectangular section mild steel of 20mm x 40mm, below both tracks. That'll also allow for adapting mounts from seats to mounts into Vito
 
So far,
the Volvo seats are a capacitance of approx 170 nf on the occupance sensors. On the passenger seat there is no difference when I sit.
As the Vito drivers side only has wiring for the heating there's no point in worrying about the occupancy sensor of that side.

I'm still no wiser as to how the Vito circuitry is monitoring for occupance. At worst I'll have to buy a plug in fault override unit, that leaves the air bags always 'on'. It would be nice to find a cheaper way though.

When I've some time w/o rain I've to pull 2 supplies from the under bonnet fuse box to power the motors.
Both seats require a permissive, so that can be from the front dash ciggy lighter.
The drivers memory seat will require a permanent supply to hold the memory, like a HU, so that's where I'll pick that up from.
Later I may well convert the passenger seat to also have memory functions. The switches are available in Lithuania, and I'm in hope that the controllers, left or right, are the same. I will be missing the short loom for the memory connections though.

These seats feel far superior in comfort. Hopefully the heating will be good.
 

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