Seat Swap Questions

Hello,

I am in the process of swapping my interior from tan to black. To do so, I bought front seats from an '07...I have an '05. The driver seat is super easy. Literally nothing changed besides the plug design for the motor power (universal plug used for memory and non memory seats)

Passenger is a hole nother can of worms. everything changed; frame, occupant sensor, even the plug for the seat belt is flipped (same plug but now male and female plugs are on different sides of the harness)

Thankfully the side airbag is the same plug

So I am thinking that I will just move the brain of the occupant sensor from the '05 to the '07 and plug it all in to the car harness. I will remove the occupant sensor from the '07 because it is not needed anymore. The hitch is that while that will work and I won't get any warnings , I am afraid that as a result the passenger airbag will never arm even when a passenger is present. I know how to trick the occupant brain module into thinking the seat buckle is latched, but the 4 pressure sensors..

Does anyone know how to trick those 4 pressure sensors into thinking there is someone there?

My thought process is that I will just have the passenger air bags always armed even if there is no passenger. I don't care if they deploy when no one is there.

Looking at the 4 sensors, I see 3 wires leading back from each sensor to the brain. My first thought is that the sensors act like potentiometers, so a simple resistor would do the trick. If anyone has ideas or knows, please let me know. I want to have the air bags work in the event of an accident

Thank you

Swapping seat covers would probably be a lot easier!

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Last resort would be sourcing 05 seats. I like the 07+ better (the internal design for support etc

Also the frames are different so while it is possible to swap the leather / cushion, it is not ideal. It is easy for the seat bottom, but the seat back looks to be a pain. The seat backs don't inter-change between years with the way they bolt up

the 05 seat uses strain gauge sensors (4x) to sense someone sitting, where as the 07 uses the hydraulic pressure sensor.

Each of the 4 strain sensors connects to a small module, I am assuming some form of Analog to Digital converter so that the detection brain only worries about a 0-5 volt signal (just guessing here)

The 07 sensor only puts out a voltage difference as the sensor has 3 pins (Vin, Gnd, Ref).

I am going to testing for either the resistance range of the 4 strain gauges and just put a static resistor in place of them, so that the 05 harness and brain can move over to the 07 seat. This method (if it works) would make the car think someone is always sitting in the seat therefore always arming the airbag for the passenger side.

My other method I am going to try is see if what I presume is the A-D converter's working output voltage range is. I will do the same for the 07 pressure gauge.

If both have similar enough characteristics I will use the hydraulic pressure gauge and wire it to all four sensing pig tails on the 05 so that the 07 sensor works with the 05 brain. This way the air bag will arm when someone is sitting in the seat, and disarm when no one is there.

These are all my hopes and dreams and here's hoping it all works the way I am hypothesizing. If anyone has knowledge on this stuff feel free to join in!!

So I finally got around to testing the pressure sensor of the 07 seat since its pins are labeled 5V Vout Gnd. The Vout reads 4V when the sensor is unloaded (no fat asses sitting down). When pressure is applied to the hydraulic bag, it goes down to less than 2V.

Now I know the sensor trend for the 07 seat I then got to testing the 05 sensor

The sensor output has 4 pins. Looking down the barrel (also reference my hand drawing) with the connector tabs oriented as drawn, only pins 1,2 and 4 are used. Pin 1 is yellow, Pin 2 is Red, and Pin 4 is Black or Brown.

I assumed the black/brown wire is Gnd, and that Either red or yellow are 5V and Vout (all wild assumptions). I was close.

Black/Brown(4)-Gnd

Red(2)-Vout

Yellow(1)-5V

The trend of the 05 sensor conveniently is different (Yay).

Unloaded I was reading 1.6V. Pressing the load cell I was reading 4.5V.

So Good news is the sensors act similarly. Whatever signal I come up with I just need to attach at a node to all 4 sensor plugs and have the brain from the 05 seat just be zip-tied under the 07 seat.

Either I need to invert the signal with some transistor set up (still brain storming) or just hook the 5V signal with a resistor to all the Vout lines so that the car thinks someone is always sitting on the seat. With the latter idea I would have to trick the car that the seat belt is always buckled too. Any ideas to invert the signal would be great, I will be looking into it now.

So I finally got around to testing the pressure sensor of the 07 seat since its pins are labeled 5V Vout Gnd. The Vout reads 4V when the sensor is unloaded (no fat asses sitting down). When pressure is applied to the hydraulic bag, it goes down to less than 2V.

 

Now I know the sensor trend for the 07 seat I then got to testing the 05 sensor

 

 

The sensor output has 4 pins. Looking down the barrel (also reference my hand drawing) with the connector tabs oriented as drawn, only pins 1,2 and 4 are used. Pin 1 is yellow, Pin 2 is Red, and Pin 4 is Black or Brown.

 

 

I assumed the black/brown wire is Gnd, and that Either red or yellow are 5V and Vout (all wild assumptions). I was close.

 

Black/Brown(4)-Gnd

Red(2)-Vout

Yellow(1)-5V

 

 

The trend of the 05 sensor conveniently is different (Yay).

Unloaded I was reading 1.6V. Pressing the load cell I was reading 4.5V.

 

 

So Good news is the sensors act similarly. Whatever signal I come up with I just need to attach at a node to all 4 sensor plugs and have the brain from the 05 seat just be zip-tied under the 07 seat.

 

 

 

Either I need to invert the signal with some transistor set up (still brain storming) or just hook the 5V signal with a resistor to all the Vout lines so that the car thinks someone is always sitting on the seat. With the latter idea I would have to trick the car that the seat belt is always buckled too. Any ideas to invert the signal would be great, I will be looking into it now.

You can usually invert any signal with a 4 pin relay. Not sure if that work given the situation though with different voltages, good luck!

So, I got around to testing the '07 sensor with an inverter chip i had laying around, and it seems to work. Just leaning on it with my hands while the hydraulic bag is on a desk top, I am able to get the voltage to drop down to below 2 volts on the output. So When that output is sent to the inverter. When the 2 volt threshold is broken, the output of the inverter goes from 0V to 5V. I will give that a shot from the start (no way of knowing until I start up the car since the system doesn't indicate anything until engine is running). I do want to figure out a more dynamic way so that it doesn't act like a switch. For that I might need to look into some sort of OpAmp set up or something. For now, it is enough to keep going forward. Ultimate fall back is still wiring it so the sensing wire is always given 4-5V so that the brain always thinks someone is sitting down.

With this whole swap, I want the airbags to be fully functional for passenger safety. Once this is tested on the car with it running, I will report back

So, I got around to testing the '07 sensor with an inverter chip i had laying around, and it seems to work. Just leaning on it with my hands while the hydraulic bag is on a desk top, I am able to get the voltage to drop down to below 2 volts on the output. So When that output is sent to the inverter. When the 2 volt threshold is broken, the output of the inverter goes from 0V to 5V. I will give that a shot from the start (no way of knowing until I start up the car since the system doesn't indicate anything until engine is running). I do want to figure out a more dynamic way so that it doesn't act like a switch. For that I might need to look into some sort of OpAmp set up or something. For now, it is enough to keep going forward. Ultimate fall back is still wiring it so the sensing wire is always given 4-5V so that the brain always thinks someone is sitting down.

 

 

With this whole swap, I want the airbags to be fully functional for passenger safety. Once this is tested on the car with it running, I will report back

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I did, but in a hack way.

I disassembled the 05 passenger seat and removed the occupant module, the 4 strain gauges, and the seat belt receptacle and the piece that is inserted into the receptacle (on the belt side). I put worm style hose clamps around each strain gauge to make the car think someone is always sitting. Then zip tie the 4 strain gauges under the 07 seat, along with the 05 seat belt receptacle with the belt clip in the receptacle. Add the 05 occupant module and plug it all in.

It's a bit tight and you'll have to get creative on placement of everything but it all fits.

This will have the airbag on at all times regardless of passenger.

Keep the 07 module because I am working on making something that will get rid of the strain gauges and hopefully the seat belt buckle too.

Drivers seat you will need to transfer the 05 seat belt receptacle and **important** pull the drivers seat location sensor (it is riveted to the bottom of the seat). Then just plug the location sensor in and zip tie it somewhere under the seat. I pulled a black 05 belt receptacle from the junk yard so that I didn't have to use the old tan one since the 07 uses a different plug.

Thanks, this sounds exactly like what I was thinking. I plan on drilling and tapping the 05 strain gages. Thru hole in the lower jaw of the strain gauge with tapped there's on the upper jaw. Insert bolt with loctite and tighten reach bolt until the sensor believes the seat is occupied. I'll keep all pieces to try your new fix you come up with. Thanks again

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I used your method with the clamps and it shows passenger airbag on.

The airbag light is still on the dash like a fault maybe?

Did you have to turn it off or have the dealer reset it?

I tried torque pro and there was no faults.

Also, I have a few seat bases so I have the make plugs. Maybe we can swap some parts and get us both set up

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I bought this back when I was first messing with this. It allows for clearing and reading of airbag faults so that I wasn't shooting in the dark. You can start by unhooking the battery for a few minutes and see if that resets it.

And the plugs that are attached to the strain gauges are what I need. I can get them from the junk yard easily but they still have the AD converter integrated. If I can find that plug but as a pigtail form, them I'd be happy!

I bought this back when I was first messing with this. It allows for clearing and reading of airbag faults so that I wasn't shooting in the dark. You can start by unhooking the battery for a few minutes and see if that resets it.

 

 

And the plugs that are attached to the strain gauges are what I need. I can get them from the junk yard easily but they still have the AD converter integrated. If I can find that plug but as a pigtail form, them I'd be happy!

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This is the thread for all the 2005 seat swap/passenger occupancy sensor/airbag questions.

Jaylew, do you think it's possible to transplant the strain sensors into another seat? From your posts I'm unable to decipher whether they are located under the seat cushions, in the seat cushions, or something else.

I interested in getting a matching Recaro for my passenger side.

Hey Enlight,

Are you saying this thread is the only one? or were you trying to link to another thread?

In either case the strain sensors are bolted to the seat bottom frame. So you can remove the seat cover, and cushion to expose the raw frame. One side of the strain sensors are bolted to the seat bottom frame. The other side of the strain gauge is bolted to the seat rail.

I still plan to figure out a way to make more modern occupant sensors out of both MY07+ subies and other seats work with the occupation system. Life has kind of gotten my distracted in the mean time.

To have the airbag still work (but always armed) follow my description in post #9. I have been running that no problem for a while now. It does require dismantling your passenger seat to make it work. Not the most elegant solution but it works for the time being.

Hey Enlight,

Are you saying this thread is the only one? or were you trying to link to another thread?

I meant to say that this (your) thread is probably the one that addresses the occupancy sensor dilemma the most directly since it targets the occupancy sensor itself. I know some other members have swapped out entire seat bases between model years but that, unfortunately, doesn't work for users that want aftermarket seats.

In either case the strain sensors are bolted to the seat bottom frame. So you can remove the seat cover, and cushion to expose the raw frame. One side of the strain sensors are bolted to the seat bottom frame. The other side of the strain gauge is bolted to the seat rail.

Ok, I think I'm beginning to see now. In any case, I will have to take it apart myself anyway after I receive my new Recaro passenger seat. I will see whether it's possible to retrofit the strains sensors to the new seats. If I get lucky it might just require tapping holes and installing the sensors as you described.

I still plan to figure out a way to make more modern occupant sensors out of both MY07+ subies and other seats work with the occupation system. Life has kind of gotten my distracted in the mean time.

An idea I had considered was swapping out the Airbag Control Module located in the dash below the radio from the 05 we have to an 06MY+ one. Changing this module would enable you to use the 06+ bladder style occupancy sensors. From the little research I did, the other airbags (steering wheel, dashboard, side curtain) are the same between 05 and 06+. The differences are the passenger and driver seat airbags and occupancy sensors. If these are the only differences, it might be possible to just swap the Airbag Control Module, the occupancy detector harness, and the seat airbag harnesses. However, I'm not sure whether the 06+ Airbag Control Module can connect to an 05 ECU without issue.

Thanks for your reply.

An idea I had considered was swapping out the Airbag Control Module located in the dash below the radio from the 05 we have to an 06MY+ one. Changing this module would enable you to use the 06+ bladder style occupancy sensors. From the little research I did, the other airbags (steering wheel, dashboard, side curtain) are the same between 05 and 06+. The differences are the passenger and driver seat airbags and occupancy sensors. If these are the only differences, it might be possible to just swap the Airbag Control Module, the occupancy detector harness, and the seat airbag harnesses. However, I'm not sure whether the 06+ Airbag Control Module can connect to an 05 ECU without issue.

That is an interesting approach. I hadn't thought of that. When I finally get around to exploring junk yards here in Massachusetts (I moved here from PA recently) I will grab an 07+ control module. I already have the 07+ occupant module.

Another idea for "airbag always on" would be a simple voltage divider circuit so that the sensing wires are always getting a 5V signal making it think someone is there. Then there is no need to keep the strain sensors clamped under the new seat.

either way, seems like a possible approach. I still want to work on something that inverts the signal so that the bladder style can be used with '05 occupant modules.

When I get a chance I will look into it and report back. I'll start with the resister method because getting rid of all the strain sensors would be an ideal start.