W126 Front seat heater no low setting
 

Hi, I have front and rear heated seats in my SEL.

The rears are working fine, you have low and high heat settings which are indicated by either 1 or 2 led's on the switch.

On the front though you can only select high or number 2. It automatically drops down to low after a preset amount of time but you cannot manually select low, you push the button but the led doesn't come on and no heat appears.

Any thoughts?

Cheers
Matt.

Try pushing the button the other way. pushing down activates the "two" lights or "quick warm-up" and up activates the "normal" mode.

Sorry if my post wasn't clear enough.

Pushing down gives me high with 2 led's and pushing up used to give me low heat and 1 led. This still works on the rear seats but not on the fronts anymore, however it automatically drops down to low after it's been on high for a while as normal.

Cheers
Matt.

Matt,

I would guess the switch is going south, er north in your case ;). If you have a little extra time you could try swapping the switches to see if the problem moves with the switch.

Hi Mike.

Just to clarify my post again, it's both front heated seat switches that are playing up, both rear's are fine.

I would suspect something common as I doubt that both switches are faulty and given that it auto switches to low after a while the majority of the circuitry is there and working.

Cheers
Matt.

I still lean toward the switches Matt. The fronts are located at the optimal location to have something spilled on them, while the rears are high in the door. Anyone spill a little coffee or soda lately? Might be worth trying to clean them out with some CRC contact cleaner.

Hi again Mike.

Definitely no spillage, there are no drinks or food ever in my car - I am a bit anal like that :-)

I will pull the switch panel and inspect over the weekend.

Matt.

I thought about this on the way into work this afternoon. I can't recall whether the 560 has a single relay for the heaters or a separate relay front and rear. If dual relays, the front could be acting up. No access to the manuals from the office so I can't cut sign for you.

It appears to be a relay per side that controls both high and low. I have hopefully linked a pic from the electrical guide on the cdrom.

Cheers
Matt.

http://homepages.paradise.net.nz/mattpete/diagram.jpg

Matt,

I wish I knew how to post the page from the manual, but I don't. I'm looking at it right now in another window. The diagram you posted appears to be for models through 87. On page 5 is the diagram for models starting 10/88. On that diagram the only common factors I see are the front control module #N25/5 and the connector block #X30.

Good luck.