Why aren’t they switching on automatically on Jaguars, which were made before 2009? Heated windows and mirrors are activated on a cold start, but heated seats are activated only manually.
My Jaguar X-Type and one of my client’s S-Type lacks this feature.
This post is my thoughts on how to get it working automatically on a cold winter day.
Alright. Apparantly, it is the CLIMATE CONTROL MODULE (CCM) function to measure outside temperature and control the relays, activating different heating coils. Here is a graphic diagram just for the referrence.
But it is not connected to the heated seats anyhow. At all!
OK… Let’s take a look at the Heated Seats Module than and find out how it actually operates.
Here is a diagram for the heated seats module, which shows that it can be activated only manually. No external signals or CAN connections. Plain switching to ground through the dashboard button and 2 leds to indicate the intensity.
I have found out what connector types this SCM (Seat Control Module) uses. It’s Aptiv (Delphi) PCB mount 12160446 and 12065425. Thought of trying to build some kind of a device I could stick in between the SCM and connector, but the PCB mount version of connector costs $45. Either will hook up to the wires, or get a male – female connector.
Let’s formulate what we want to achieve to move further.
What we need
- Operate only when the car starts
- If the (outside / inside / seat) temperature is lower than X degrees, switch on the heated seats.
- Not to complicate the task, lets turn on both heated seats, even if there is only 1 person in the car.
- Switch off? Should it also automatically turn itself off when reaching a predefined temp or time interval?
What we have
- Two manual switches to GND, each connected to a separate Seat Heat Module.
- Two temperature sensors in each seat cushion.
What we can do
- Read temperature sensor value (T).
- If T < X degrees turn on heating.
How do we read a sensor value?
The sensor in qustion is a resistive component run by 2 wires. It just changes it’s resistance depending on the temperature.
You know what?
I have changed my mind.
While deciding on how to approach this task and thinking of how to hook up to the existing temp sensor… I have decided not to mess up with SCM, because I suspect that that sensor uses 12 V and I’d need to convert that into 0 – 1 V. And getting to the SCM can mean I’d need to get the seat out. I want to make it the easiest way possible to install.
I will have my own ambient temperature sensor and will place the adapter somewhere near the GEM. The adapter will be activated with KEY II position (that’s when Climate Control unit and SCM are activated), and will switch heated seats if temperature is lower than 10°C. And I want it to vary in intervals it will work on a really cold winter day or when it’s slightly chill outside. Also I’d like to make it more smart and change heat levels from max to min by itself after a preset interval.
Operation logic
