OEM Heated seats and Aftermarket wiring + switch

[Geordman]

I have Caravelle T5.1 leather front captains seats in my T6, these are factory heated. I've already taken a punt with a T5.1 heater control unit with heated seat buttons but it didnt control the heating direction properly in my T6 (fiddling and recalibration with VCDS didnt help). And i've come to the conclusion that trying to wire up these seat to be OEM is a can of worms/expensive.

Has anyone had success getting OEM seat elements powered using some simple aftermarket wiring, i'd rather not blow the elements or fry my ass.
Info on switches used, relays and appropriate fusing would be super helpful.

Thanks in advance!

I'm thinking a couple of switches like these (attached) added into blanks on the dash would be an acceptable compromise:

 

[roadtripper]

This may help:

https://www.t6forum.com/threads/heated-seats-wiring-diagram.15987/

That shows a 25A fuse so moderate current.

I wouldn't expect the type of switches you suggest will have the current handling so you will probably need a relay.

You'd also want it to go via ignition to avoid battery issues so you are probably looking at picking up an ignition switched circuit from the dash fusebox and a local ground (for the indicator light)and then cable down to under the seats with a relay and pick up a high current feed there and a local ground.

 

[Geordman]

Many thanks, that does help. I thought similar about those switches, but if i do use a relay im not sure how the switch would then be able to control the current (for high and low) perhaps only on/off would be possible?

 

[roadtripper]

That's going to be your problem.

If you look at G20 on the diagram there is a temperature sensor in one of the two heating elements and the control module will be using that to regulate the temperature.

What I don't know is if the sensor is just used to do the "lower" settings or if it's always used even on the high setting - there is a danger if it's always used in the OE setup that if you just connect permanent power to the heater elements they will overheat.

So unless someone can confirm if they are safe to use unregulated I'd be very wary of trying this.

 

[Deaky]

You would be better off removing the OEM heating pads and fitting an aftermarket kit. You could retain the OEM pads and fit the rest of the components to use them but this would ne a more complex and expensive task

 

[Geordman]

That's going to be your problem.

If you look at G20 on the diagram there is a temperature sensor in one of the two heating elements and the control module will be using that to regulate the temperature.

What I don't know is if the sensor is just used to do the "lower" settings or if it's always used even on the high setting - there is a danger if it's always used in the OE setup that if you just connect permanent power to the heater elements they will overheat.

So unless someone can confirm if they are safe to use unregulated I'd be very wary of trying this.

Spot on! Thats exactly what i need to know, if someone else has had success without blowing the elements!?
Another option i suppose is to use a OEM wiring as per the schematics, a G20 control module/relay and use switches in leu of the correct heater controls. But not sure whether the G20 is the brains of it and the heater controls do more than just change the setting?
I would need to fiddle with a multimeter on a known working set to understand that, my bro has a mk7 golf with heated seats… i bet i has the same G20, that might give me clues…

You would be better off removing the OEM heating pads and fitting an aftermarket kit. You could retain the OEM pads and fit the rest of the components to use them but this would ne a more complex and expensive task

I dont disagree, just not sure i can be arsed to pull the seats apart.

 

[roadtripper]

G20 there is nothing to do with any active control, it's just showing a heater pad with a thermistor (maybe more than one) built in.

J774 is the control unit.

 

[Geordman]

U think the J774 might be what i mean, one of these (attached)