Retrofitting Heated Seats into an '05 997 C2S

[petza914]

Years ago, I purchased Adaptive Sport Seats plus for my 2005 997.1 C2S and they work great, including all the memory functions.  These seats were actually heated, even though my car didn't have the heated seat option, so lately, I've been trying to get the heated seat elements to work.  I ordered and now have the climate control module from a heated seat car with the 2 seat heater buttons on the left and right sides.  Hoped just installing this and coding the A/C module and Gateway to tell the car it had heated seats would do the trick, but it didn't.  Looking deeper, the wiring that goes to my seats only has the pair of large gauge wires for seat power, but not the other pair that go to the seat heaters.  I've now fabricated these pigtails and integrated them into the OEM seat connector, but need to connect them to a control switch.  I could simply add a switch that gets switched 12v power and connect that to my pigtail to have Hi heat on or off, but would really like to get the factory controller working for a cleaner look.

 

Even though I've coded the car for Heated seats, I'm still not getting any lights on the heated seat control buttons on the climate control unit.  Does anyone have a wiring diagram for the back of the climate control unit to show what pins and what wires control what functions?  I also ordered the wiring harness from a center console from a heated seat car, thinking I might need to swap that and that the two unused connectors in the back of the unit might be part of the heated seat circuit, but it goes too many places and I'm not willing to tackle the swapping the harness job.  It also only has the same large black and large red connectors for the back of the control unit, so now I'm also wondering what the two unused areas of the back of the climate control are used for as neither my car, nor my wife's car (which has Sport Chrono but not heated seats), nor the wiring harness from a car with heated seats has connectors for these other large pinned openings in the back.

I've now created a two wire pigtail to the factory connectors that go to the heating elements in the seats and when I put 12v across them, both the bottom and back of the seat warm up.  I'd really like to figure out a way to have the heated seat switches on the OEM climate control send the signal even if I have to run wiring to the pigtails I've created on the seats themselves, but can't get the buttons to light up, which means I can't test the pinouts or wiring with a meter to know which wire sends the signal for the heat to each side.

Anyone know the wiring color and whether it's in the large black connector or large red connector behind the HVAC controller?  Any idea why the heated seat lights won't come on at all, not even blink then shut-off?

 

Any help would be much appreciated.  Thanks.

 

[Loren]

 

Wiring diagrams change by model and year.

Exact model and year of your car please?

Exact model and year of the donor car please?

[petza914]

6 minutes ago, Loren said:

 

Wiring diagrams change by model and year.

Exact model and year of your car please?

Exact model and year of the donor car please?

As stated in the title and my post, my car is a 2005 997.1 C2S.  The HVAC controller with the heated seat switches is from a 2006 (not sure what model) and it controls all of the climate control functions perfectly. 

 

Hope that helps.

[Loren]

The seat heaters are controlled by the Onboard Computer, Network control unit.

The heating elements get power from the power distribution (one power wire and one ground wire (brown).

 

Do the power connections and fuse connections exist?

[petza914]

From what I've been able to gather, the heated seats are not on their own fuse and share the same circuit as the windshield washer squirter, which does work. 

 

Since the red and black connectors look to be the same between a harness from a heated seat car and a harness from a non heated seat car, I was hoping that by coding the heated seat option that at least the lights on the seat heater switches would come on, but no joy. 

 

I haven't counted the number of wires going to each plug in the wiring harnesses - maybe that's my next step. 

[petza914]

Comparing the 2 harnesses, the large black plug and large red plug from my original wiring harness and the new heated seat wiring harness I bought both have the exact same # of wires going to them - 11 wires in the black plug and 15 wires in the red plug, so don't know why the heated seat switch lights won't come on.

[petza914]

Have another issue as well.  Took apart the yellow main connector for the driver's seat and it does not have the extra pair of large male spade connectors for the seat heater like the passenger seat did - just one pair, which I assume are for the main power to the seat, although it also looks like most of the wires in that connector are brown, which would mean grounds.  It's possible that everything is powered from the large black box mounted to the bracked under the seat, and that the main yellow plug just grounds all these connections to complete the circuit in the seats. 

 

At this point, I'm going to reassemble things the way they were and try and gather additional info to possibly undertake this again in the future with additional info. 

[DustyM]

Sorry to drag up an old post but did you ever find a solution?

[petza914]

Dusty, sorry, no, I never dove back in from the last time I was looking into this here.  I still have all the parts sitting in a box on the workbench.  If I lived where it was colder, it might have been further up the list, but most of this summer was spent doing a push pull engine swap in my 928.  Everything else got back burnered.

[DustyM]

Thanks for the reply, I'll be using my car through this winter so will persevere. Currently I have installed heated seats and swapped the HVac unit for one with the seat heater buttons and enabled the function in the gateway with durametric. 

 

Unsurprisingly it doesn't work as I have no power running to the seat heaters through the yellow plug on the seats, these wires will need to be run, but from where I'm not sure yet.

 

I did note though that if I press the seat heater buttons it generates an error code in durametric, so the ECU must be recognising that the button has been pressed although no lights come on.

 

Vehicle Electrical System:

 

8035

Left Seat Heater

8036

Right Seat Heater

 

Need to find a detailed wiring diagram.

 

Just to add that I'm fitting these in a 2007 987 Cayman S

 

Cheers

 

Edited September 19, 2019 by DustyM
More info

[petza914]

14 minutes ago, DustyM said:

Thanks for the reply, I'll be using my car through this winter so will persevere. Currently I have installed heated seats and swapped the HVac unit for one with the seat heater buttons and enabled the function in the gateway with durametric. 

 

Unsurprisingly it doesn't work as I have no power running to the seat heaters through the yellow plug on the seats, these wires will need to be run, but from where I'm not sure yet.

 

I did note though that if I press the seat heater buttons it generates an error code in durametric, so the ECU must be recognising that the button has been pressed although no lights come on.

 

Vehicle Electrical System:

 

8035

Left Seat Heater

8036

Right Seat Heater

 

Need to find a detailed wiring diagram.

 

Just to add that I'm fitting these in a 2007 987 Cayman S

 

Cheers

 

Interesting about the error code. Are those 8035 and 8036 the codes you get. I didn't check Durametric for those errors when I was playing with it. With error codes it means you have power to the buttons, which is good to know, but I guess since it can't complete the circuit it won't illuminate the buttons. 

 

I hope you can figure it out. 👍

[DustyM]

Yes those are the error codes.

 

I assuming that the buttons must send a signal to a controller or relay somewhere as the wires to those switches won't carry the sort of current needed by the seat heaters.

 

I suspect that there is no wiring from that controller or relay to the seats

 

If I can find out where the seat heaters get the power from i stand a chance of making it work I think.

[DustyM]

From a post on another forum

 

Quote

Now I just need to run the wires - which is also not as easy as first suspected. I need to get access to the fuse box that's above the passenger side foot well and run two wires from there to the Vehicle Electrical System Control Unit which is somewhere by the drivers side fuse box (I believe). I haven't located the VESCU yet, and the fuse box is behind an obstruction I haven't figures out how to get past yet either. Once the wires are run from there, I need to run wires from the VESCU to the yellow connectors on the seats. Pin 8,9 and possibly 13 - but I'm still finalizing wiring diagrams for that part.  

I really need the most help locating the VESCU at the moment and figuring out 1) how to access it 2) what size wires to run from fuse connections to the VESCU, and then again what size wires to run from the VESCU to the seats themselves.