You do not need to remove the seats to remove the upholstery. I retrofitted heated seats using a kit from eBay. I have the Limited leather seats, so others may be slightly different. That said, the following pictures may offer some insight into how to access your factory heaters, or help someone else retrofit heaters to their own seats.
This kit is fed by 3 wires: +12V, ignition sense, and ground, just like the OEM version. I found my car had a dedicated heated seat fuse and a switched wire dedicated to the heated seat circuit, but it ended at the connector behind the DS kick panel. The cross-body harness did not include those wires. So I ran 3 #12 wires under the carpet, following the cross-body harness in the same channel, but in their own plastic wire loom. I cut the OEM +12v wires from the supply-side of the connector and spliced them into my new wires with some insulated spade connectors and added my ground to the bolt grounding the rest of the dash to the body. I didn't take pictures of that because by the time I was done it was dark and I didn't think of it until I was reassembling everything.
Today I installed the pads and switches. Removing the leather upholstery was not especially tricky, but does require strong fingers. The edges of the upholstery are secured with plastic (nylon?) "j-hook" strips that lock to the edge of the frame. A bit of weight on the seat helps get things started, but once one end is started, the rest slides off like a zipper.
The pads are labelled -- in German:
I honestly don't know why left and right would matter, but the seat cushion is the part with the temperature sensor wire, strategically positioned where pressure will make it matter the most .
That black band is some serious industrial-strength velcro. It will quite literally rip from the foam cushion before it will let go of the loop strip sewn to the leather. You have to work gently an inch at a time to release it.
Shortly after taking the above picture, I realized that the tape was double sided. Actually, that's not entirely true: I thought it might be double sided initially but darned if I could get the backing off the tape. However, perseverance prevailed:
It does a nice job of holding the pads in place while reinstalling the upholstery. The pads are made of heater wire sewn to the back of some thin stiff felt. The cut-outs were close to the velcro, but I trimmed them a bit for better clearance:
The control unit is built into the switch. It is a tight fit -- tighter than I realized looking at the photos in the ad, but very careful measurements proved it would just fit in the seat-side switch housing, approximately where the stock switch would have been located. The bottom of the control actually protrudes beyond the edge of the housing, but not until it clears the seat frame, so it doesn't matter. I apologize in advance, I didn't realize this picture was a bit blurry and it's the only one I took:
However, you can see the end result clearly, and that's what really matters anyway:
One nice thing about this kit is they didn't scrimp on connectors, making it easy to push wires through small spaces and connect it all up afterwards. I guess the kit is designed with the thought that someone would be installing the controls at a greater distance -- in a console or even the dash. Each side had a long extension between the pair of pads and the rest of the wiring, but I really didn't need several feet of wire coiled up under the seats. So I omitted that and just plugged the heater pads directly into the other end.
The seat back assembly is secured with similar j-hook strips, but hooked to each other then covered with the map pocket which is secured with standard "Christmas tree" fasteners. The backing is hard-board, so make sure you use the proper tool to grab the fastener. Don't pull on the map pocket or you might tear a large hole in the backing.
With it the first seat assembled, it was time to try it out!!! I fired up the car, set the control to 5 (maximum) and sat down to wait for a warm butt. Which didn't happen It worked fine when I tested everything last night??? I hooked up an ammeter to see if power was flowing -- nada. I swapped in the other control -- nothing. I swapped in the other set of pads -- Success!! They immediately started to warm up and the ammeter showed a little over 5 amps of current draw. WTF??? How could I have burnt out or damaged both the seat and the backrest pads during installation???
About then my eye fell upon the extension wire that I had deleted. Son-of-a---- They crossed the wires between the connectors! I plugged in the extension and confirmed that the seat was soon toasty. Time to get out the set of terminal tools and correct the order so I could delete the extension:
Unrelated to the heated seat, but another common problem seems to be failed lumbar supports. You can see the lumbar support motor mounted to the right side of the passenger backrest frame. The motor on top drives a screw mechanism that moves the cables in and out. The cables in turn tension the black "belt" across the bottom. If the plastic housing breaks, the motor will spin but the cables won't move anymore. All you have to do is find a way to hold the two halves together again. I used one of these industrial strength zip-ties to fix the driver's side, so while I was in there, I added one to the passenger side to forestall future problems:
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Sun Nov 24, 2013 4:08 am
