Seat removal - electrics

[Psm1975]

I thought I’d done all the research I needed, but apparently not.

Today I’ve removed the seats in order to run my 12v feed to my leisure battery, and also the EHU wiring.

There’s a load of wiring under the seat, which the forum has shown me how to ‘hide’. What I wasn’t expecting were the 4 connectors that go into the actual seat.
2 of these connectors go to the seatbelt, and 2 go into the seat cushion.
The seat doesn’t have airbags, or pre tensioners from what I can see. I can only presume they are to show if seatbelts are plugged in or not. ??

What are people doing with them. I’ll be fitting a swivel in the not so distant future so would like them gone.
I’ve tried to see the wiring in the VIP section, but can’t locate it.

Any ideas?
Thanks.

 

[Steve Hales]

The ones going to the seats are for the heated seats (if you have them) and occupancy sensors I think and the others are for the seat belts, don’t think it’s that easy to loose them.

 

[Psm1975]

I don't have heated seats.

Having done some research on this, including looking at the wiring diagram. The 4 connectors are to do with the 2 occupancy sensors, and the 2 seatbelt sensors. The occupancy sensor is in series with the seat belt sensor, which then goes to earth.
The occupancy sensor is NORMALLY OPEN and the seatbelt sensor is NORMALLY CLOSED, so the 'system' is an open circuit when the seat is empty, and no seatbelt. When you add weight to the seat, you close the circuit, and the beeping starts after a duration. If you then plug the seatbelt in, you open the circuit again and the beeping stops.

By not connecting these 4 connectors, you lose the ability to see if your passengers have their seatbelts in, but you could just look left and see as well. I'm happy to leave these disconnected.

 

[ombracs]

I don't have heated seats.

Having done some research on this, including looking at the wiring diagram. The 4 connectors are to do with the 2 occupancy sensors, and the 2 seatbelt sensors. The occupancy sensor is in series with the seat belt sensor, which then goes to earth.
The occupancy sensor is NORMALLY OPEN and the seatbelt sensor is NORMALLY CLOSED, so the 'system' is an open circuit when the seat is empty, and no seatbelt. When you add weight to the seat, you close the circuit, and the beeping starts after a duration. If you then plug the seatbelt in, you open the circuit again and the beeping stops.

By not connecting these 4 connectors, you lose the ability to see if your passengers have their seatbelts in, but you could just look left and see as well. I'm happy to leave these disconnected.

Hello psm1975, do you think that you only loose the ability of passengers to have their seatbelt on ? there is not a risk of NO deployment of front dash airbag because it looks that nobody is seated ?
I ask this question because i have swapped front double seat (with airbag and occupancy sensor ) with a single seat (no airbag and no occupancy sensor ). I have resolved airbag light with a resistor and i didnt plugged any belt or occupancy sensor like you but i m worried about the front dash airbag ... somebody online think that without occupancy it will not deploy in case of accident .... do you have some info ?

Thank you
Filippo

 

[Psm1975]

Here’s the wiring diagram for the seatbelt connectors.
The pressure pad has a normally open switch. The seatbelt has a normally closed connector.

With no-one sat on the seat, the signal gets as far as the pressure switch which is OPEN and no signal gets to earth.

When someone is sat on the seat with their seatbelt on, the signal from the control module passes through through the pressure pad (now CLOSED) and gets as far as the seatbelt which due to being plugged in, (now OPEN.)
Therefore no signal gets to earth.

When the connectors are unplugged, no signal can pass through them so no signal gets to earth. This is the same as someone sat on the seat, with seatbelt on. Therefore airbags will deploy.

The only alternative situation is for the signal to get to earth, caused by weight on the seat (causing the pressure switch to CLOSE) and no seatbelt plugged in (leaving that switch CLOSED). This is what triggers the alarm.

 

[ombracs]

Here’s the wiring diagram for the seatbelt connectors.
The pressure pad has a normally open switch. The seatbelt has a normally closed connector.

With no-one sat on the seat, the signal gets as far as the pressure switch which is OPEN and no signal gets to earth.

When someone is sat on the seat with their seatbelt on, the signal from the control module passes through through the pressure pad (now CLOSED) and gets as far as the seatbelt which due to being plugged in, (now OPEN.)
Therefore no signal gets to earth.

When the connectors are unplugged, no signal can pass through them so no signal gets to earth. This is the same as someone sat on the seat, with seatbelt on. Therefore airbags will deploy.

The only alternative situation is for the signal to get to earth, caused by weight on the seat (causing the pressure switch to CLOSE) and no seatbelt plugged in (leaving that switch CLOSED). This is what triggers the alarm.

View attachment 265934

thank you very muche for the info !!

 

[VWT6.1LWB]

@Psm1975 you're a legend. I've brought a jennings double swival for my t6.1 and thought I'd be returning it due to these four connections as there is no way of connecting them in the seat after fitting. Thanks for the info and diagram above, I'm happy to leave them disconnected now

 

[andrew2767]

I thought I’d done all the research I needed, but apparently not.

Today I’ve removed the seats in order to run my 12v feed to my leisure battery, and also the EHU wiring.

There’s a load of wiring under the seat, which the forum has shown me how to ‘hide’. What I wasn’t expecting were the 4 connectors that go into the actual seat.
2 of these connectors go to the seatbelt, and 2 go into the seat cushion.
The seat doesn’t have airbags, or pre tensioners from what I can see. I can only presume they are to show if seatbelts are plugged in or not. ??

What are people doing with them. I’ll be fitting a swivel in the not so distant future so would like them gone.
I’ve tried to see the wiring in the VIP section, but can’t locate it.

Any ideas?
Thanks.

View attachment 260965View attachment 260966

Hi Psm1975. Can you link to where you got help from the forum about hiding the wiring please. I need to take out the front seats altogether and have as flat a base as possible to allow me to carry long loads inside the van. TIA

 

[Psm1975]

I actually did the research myself. I believe I uploaded a wiring diagram showing that the 4 sets of wires aren’t needed. Especially in your case if you’re removing the passenger seat!

 

[3RGK]

Here’s the wiring diagram for the seatbelt connectors.
The pressure pad has a normally open switch. The seatbelt has a normally closed connector.

With no-one sat on the seat, the signal gets as far as the pressure switch which is OPEN and no signal gets to earth.

When someone is sat on the seat with their seatbelt on, the signal from the control module passes through through the pressure pad (now CLOSED) and gets as far as the seatbelt which due to being plugged in, (now OPEN.)
Therefore no signal gets to earth.

When the connectors are unplugged, no signal can pass through them so no signal gets to earth. This is the same as someone sat on the seat, with seatbelt on. Therefore airbags will deploy.

The only alternative situation is for the signal to get to earth, caused by weight on the seat (causing the pressure switch to CLOSE) and no seatbelt plugged in (leaving that switch CLOSED). This is what triggers the alarm.

View attachment 265934

I think you’re very close on the logic, but there’s one important detail that might change the conclusion.

You’re right that:

• The pressure pad is normally open and closes with weight
• The seatbelt switch is normally closed and opens when latched
• A path to ground only exists when someone is sitting and the belt is unlatched → which triggers the warning

That part all checks out

Where I’m not fully convinced is the conclusion about unplugged connectors meaning “airbags will deploy.”

Electrically, an unplugged connector does look like “no path to ground,” which is the same as either:

• seat empty, or
• seat occupied with belt latched

But that doesn’t necessarily mean the airbag system interprets it as a valid “safe” state. On a lot of VAG systems, unplugged or out-of-range signals are treated separately (either ignored for logic or handled via plausibility checks), even if they don’t always throw a DTC.

Also, the belt warning logic and airbag deployment logic aren’t always the same thing—even if they share inputs.

I ran VCDS on mine and didn’t get any faults either, which suggests the circuit isn’t being monitored as a fault in this case, but I’d still want to confirm using live data (measuring blocks) to see how the module actually interprets each state.

So I’d say:

• Your ground/no-ground logic for the warning system is spot on
• But “therefore airbags will deploy” might be a step too far without confirming how the control unit interprets an unplugged input

Would be interesting to see live data for:
seat occupancy + belt status + unplugged condition to confirm