This project started out as a whim to experiment with a little tartan in the cabin. Having recently been to a Porsche show and seen so many classic and homage cars sporting tartan interiors I thought it might be nice to brake up the general blackness of my old “black on black”. However, I was reluctant to re-upholster my original 997 seats which were in OK original condition.
So I started out searching for a set of cheap replacement seats which I could then get re-upholstered in tartan. An option to acquire some very good condition 991/981 seats from a 2014 Cayman came up and so I jumped in, unsure whether this swap was actually possible. Turns out it is!
The original seats were the 8 way electric standard “comfort seats” for the 997. The driver seat has memory settings selected from the door. The new seats are the 14 way electric seats with heating. The seat is the same in the 991 and 981 but these were apparently from a 2014 Cayman.
Removing the old seats is really easy- 9mm socket (even though the bolts are some kind of torx) is required. If you still have the rail trim pieces on the front you will need a thin flat head screwdriver to remove these. Push the seat back, remove the front rail trim pieces by lifting the small tab with the screwdriver and sliding the trim forward. When the front two bolts are exposed they can be removed. Then move the seat forward all the way to expose the rear two bolts. These can be removed. At this stage you should disconnect the battery negative terminal before proceeding.
With the battery disconnected, tilt the seat backwards to expose the wiring underneath. My seat has a loom with two connectors – one large yellow connector and a second smaller black connector plugged into the front of the black memory module box. The yellow connector has a sliding lock which needs to be pulled out to allow the cable to be removed. It is a little fiddly. Remove both cables and remove the seat carefully from the car.
It turns out that the bolts and rails are an exact fit between the two seats. I suspect that that means that all 996, 997, 991 and all boxster/cayman seats are physically interchangeable. Also, the new seats use the same yellow main connector and this connects to the 997 yellow connector in the vehicle floor. After installing the passenger side seat and connecting the yellow connector the seat worked perfectly! All the adjusters worked (even the new ones which the 997 seat didn’t have- lumbar support and front bolster) as did the seatbelt/weight sensor setup.
Unfortunately things were not quite so straight forward on the driver’s side. Connecting the yellow connector left the black connector unconnected and unfortunately there was no power getting to the seat and no movement at all.
Consulting the wiring diagrams of the 997 and the 991 it seems that on the drivers side, the 997 main power comes in on the memory module (the small black plug) and is then routed to the seat. On the 991 (and on the passenger side of the 997) the main power comes in on the yellow connector.
The black connector to the memory module on the driver’s side seat of the 997 has the following wires;
- Heavy Red- power
- Heavy Brown- earth/ground
- Black Red- battery electronics circuit
- Yellow- CAN Comfort high
- Black- CAN comfort low These last two communicate with the CANBUS computer
To get the power to the seat, the heavy red wire needs to be removed from the connector and put into the yellow connector to the pin indicated in the picture. To do this the zip tie on the yellow connector cable needs to be cut and then the yellow housing can be removed by gently separating the tabs. This allows all the cables to come out of the housing. Similarly, for the black connector, the outer housing can be removed and then the heavy red power cable can be pulled out with its spade connector. Place the red cable into the yellow connector and the seat will now work. There is already a brown ground wire in the yellow connector so not necessary to transfer the brown wire from the black connector.
The individual spade connectors can be removed from the connector block by using a small pin or paperclip to depress the small metal tabs and pulling on the wires. They can then be inserted into the new connector slots. This is delicate- I used some magnification- but it’s pretty self explanatory when you look closely.
After providing the red power wire to the seat all the electrical controllers work as does the seat belt/weight sensor setup. However, the memory functions still don’t work. This is due to the wires to the car CanBus not being wired in. This problem and also getting the heated seats to work will be the subject of a future write-up!