Heated seats failure sl55 2003

[Jimbo095]

Hi all

Looking for some possible suggestions for the drivers side heated seat not working. Lights come on on the switch, passenger one works but drivers has nothing. Assume there's an element or two in the seat, are they replaceable or am I looking at £££ for new seats!!

Many thanks in advance!

 

[WOODYTHEWISE]

You could try swapping switches, then at least you would rule the obvious out.

 

[richard]

You could try swapping switches, then at least you would rule the obvious out.

The switches don't quite work like that, they talk to the door controller for the door that the switch is in. The fact that the red lights on the switch light, it means that the switch works. And i'm 90% sure that the lighting of the lights is fed back from the seat control modules which are the ones that power the seat elements.

There are two elements (sewn into the leather :-( ) which are fed from the seat control module

So, either seat control module, or wiring has become disconnected / damaged, or both elements failing (bottom element and back element) together which seems very unlikely (assuming they did both stop together)

I'd look underneath the seat to make sure everything is plugged in properly !



Richard

 

[Jimbo095]

Cheers peeps

Yes it has been suggested that connectors may be the issue, kids standing on the seats, adults kneeling on the base etc. Plus the previous owner was circa 22 stone so could be the culprit. I've tried looking underneath but access is pretty tricky and I can't see a great deal. I assume the seat base must come out? If it's not the connectors then I assume both elements may have failed at one time or another, is there a fix for that? The passenger seat base doesn't heat up either, only the seat back so I assume that may be kapput too?! Oh dear...

 

[cb1965]

Is it definitely an OEM system as some dealers did an aftermarket fit and these are easier and cheaper to fix. See if it's on the datacard from the build.

 

[Jimbo095]

Forgive my naivety, datacard? Would something normally show up on the star diagnosis? It was recently done for sown thing else but the nearest I see is seat adjustment which shows no faults so wondered if this could point more to one thing than the other, cable connector issue or knackered elements?

 

[richard]

Forgive my naivety, datacard? Would something normally show up on the star diagnosis? It was recently done for sown thing else but the nearest I see is seat adjustment which shows no faults so wondered if this could point more to one thing than the other, cable connector issue or knackered elements?

The data card is Mercedes' record of what the car was built with and what has been added properly. It used to be a piece of card that came with the car. Now it is entirely electronic.
The system (VeDOK) has a record showing what the car was built with (including serial numbers of all the control units installed), what options have been properly / officially added (for instance, when we retrofit options using factory components/looms we update the data card to show it) etc.
This option list gets transferred across to the parts catalogue, so the parts people can input your VIN number into the parts system and it will tell it what parts are needed for your car.

If your SL has the nice round or half/round (if heated and cooled seats) buttons on the doors then it is factory fitted. Dealers can't retrofit the proper Mercedes switches. (we can!)

I'm opting for "large driver has caused the elements in the seats to break" and your choices (if this is proved to be the fault) are thus
a) Replace the leather with new ones (and as it sounds like you have to do 3, you probably need to do all 4 to make everything match)
b) Install aftermarket seat pads under the existing ones (not as good, but functional - slightly slower to warm up as leather+old-pad is quite thick
c) (b) But using expensive mercedes pads from another model
d) Ignore it and have no heated seats

If you have a warranty on the car, then you're in luck.

Changing leather on the seats is an art though !

You check the individual seat elements by unplugging them and using a multimeter to see the resistance.

Yes, you probably have to unbolt the seats to get at the connectors

If you are near Lightwater (or near Ollie near Portsmouth) you should at least get a proper diagnosis done with Star Diagnosis, looking at the wiring and with a multimeter to check the pad resistance.

Cheers

Richard