Heated Seat Troubleshooting

I know it's an old thread, but I'm just now having the identical problem. Neither seat heats at all. Switches light up, all fuses OK.

Did anyone replace the module(s), and with what result? Or was there another solution?

BTW, does each front seat have it's own module, or just one controlling both?

Many thanks for your help. I have a 2004 Mercury Marauder, dark toreador red, light grey seats, 107K relatively trouble free miles.
 
Each seat has its own module. Since neither one works, check F1.3 (25A) in the Battery Junction Box. That fuse supplies power to both modules.

Unfortunately, the more common failure is the heating grid. You need to take the seat covers off to replace.
 
Alright, I gotta ask a question now. Both my seat heat up wonderfully, but they both don't light up. They light up telling me they're working, (Orange light) though nothing else. Every once in awhile the driver side lights up, or blinks, but not the passenger side. Is that just a fuse? Or is this something I need to take apart, find the LED, and weld a wire or something back on?
 
champ1173 said:
Alright, I gotta ask a question now. Both my seat heat up wonderfully, but they both don't light up. They light up telling me they're working, (Orange light) though nothing else. Every once in awhile the driver side lights up, or blinks, but not the passenger side. Is that just a fuse? Or is this something I need to take apart, find the LED, and weld a wire or something back on?
Click to expand...

Common problem with the switch, and will need to be replaced. Mine very early on suffered from the lights in the switches blinking, as well as many others on the site.

I believe the switch is about $35.00 if my memory serves me correctly?

;)

Mike.
 
MM2004 said:
Common problem with the switch, and will need to be replaced. Mine very early on suffered from the lights in the switches blinking, as well as many others on the site.

I believe the switch is about $35.00 if my memory serves me correctly?

;)

Mike.
Click to expand...

Thanks! I'd rather just buy a new one then go through the hassle of taking it apart. My front two switches for the windows wont light up, on the drivers side door panel. Another common problem! Well, I read a write up about how to fix them, and it seemed like a lot of work, just to get the LED to work. Then I saw on ebay that it was only $20 to get the whole Master Control Switch. Un-plug the old one, Plug in the new one, and it works! Much easier to do.
 
RF Overlord said:
Each seat has its own module. Since neither one works, check F1.3 (25A) in the Battery Junction Box. That fuse supplies power to both modules.

Unfortunately, the more common failure is the heating grid. You need to take the seat covers off to replace.
Click to expand...

A: I checked that fuse as well as the two related fuses (for lights in the switch and the control module) in the box next to the brake pedal. All are OK.

B: If only one seat didn't work, I might suspect a bad grid. But both seats went out, and there has been no one sitting on the passenger side for 99%+ of the car's life.
 
I suppose you COULD have 2 failed modules...

Can you unplug the module connector and at least verify you have 12V?

It's a 12-pin, and you want pins 6 & 7...YE/LB and WT/LB
 
replaced grid; still almost no heat

Had mechanic test driver's seat heater grid continuity - found 'open circuit' indicating a bad grid. I believe he also checked voltage re. the previous post. He said the passenger seat heater was working, though it didn't feel warm to me.

Had grid replaced, and took the opportunity for auto upholstery shop to rebuild some of the cushioning. Also replaced seat & back covers with new matching flint grey factory leather I had (fortuitously) bought back in '05 or '06. (I keep cars a long time, and I knew I was hard on driver's seats.)

I still can't feel any real warmth coming from either seat, even on 'high'. Is my memory faulty? I seem to remember the seats would get noticeably warm within a minute or so, even on the 'low' setting. What's your experience?

Also, re. the "control modules": do these just function only as on-off relays, or do they actually vary (modulate) the current going to the grids? If the latter, maybe it's worth replacing one.

Don't know what I'll do next. Maybe it's time to admit defeat and that some stuff just stops working on 10 year old cars.
 
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Seats should definitely get warm. If you can't feel the heat then the seat is not working or you're not. ;)
 
I need to buy some new switches. Passenger side has always blinked since I first got the car and past year or so the driver's side I have to press 3-10 times to just get to turn on.
 
replaced element, module OK, still no heat - wire harness problem?

Testing indicated heating element 'open circuit', which was confirmed after the element was removed from the seat. New element was checked for continuity before installation.

Still no heat. Voltages presenting to the plug are on spec, so it's not the module.

My mechanic now thinks there may be a break in one (or more) of the six wires in the flexible under-seat wiring harness that feeds the element - that's six out of the dozens in the same harness that goes to the seat motors, lumbar support, etc.

A new harness is almost certainly cost prohibitive, so he wants to remove the seat again, test for the bad wire or wires, and splice or re-wire around them.

Does this sound reasonable? Any thoughts or similar experiences?

BTW, several of earliest posts in this thread mentioned heat in the lumbar area. I was told there is no element in the seat back, only in the seat bottom, as suggested by the icons on the control button. (2004 late production Marauder). Which is it?

Thanks again for any advice.
 
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