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Subject: 4-Seat heating retrofit project: rear seat pics Author: DavidC (moderator) : member since December, 2003 : 11918 posts Posted on: 2003-12-27 23:43:52

The 4-seat heating retrofit project ('97 740iL) continues... today I got the other three seats installed and the results are terrific.

The only gotcha is that the dealer needs to reset the airbag sensor indicator in the dash, which was evidently triggered by interrupting power to the front passenger seat when it was removed.


Front passenger-side seat with heating switch in the upper right corner.


The finished result. The left and right seat heater switches are in the same location as the factory ones. Only someone who's familiar with the factory seat heating switches would be able to tell this from a factory installation!


These are the tools used to remove and reinstall the leather upholstery.


This is the underside of the rear seat bottom. Note the black wires with white plugs -- those are for the left and right side heating elements.


The large red cables are the battery mains. They go through a rubber grommet in the rear wall and into the trunk. There's just enough room to squeeze through the four sets of power supply wires for each of the four seats so that they can be connected to the fusebox in the trunk.


This is the rear driver's-side upper cushion with the heating element installed. A small notch was cut into the lower part of the foam for the power cable to sit flush with the surface.


Reinsallation of the heat-equipped driver's-side rear seatback.


The power cables for the two front seats were tucked under the plastic door trim over the carpet and snaked to the rear pass-through hole alongside the battery mains into the trunk.


Dissassembly of the rear cigarette lighter plate on the rear console, in preparation for mounting the switches for the rear seats (this is the same location for the factory heated seat switches).


The cigarette console plate with the left and right rear switches installed.


The other side of the cigarette console plate showing how the switches were mounted (using 3/4" hole saw bit and a pair of vice grips to brace it).


The carpeted panels underneath the console had to be removed so that the carpet over the floorhump could be lifted to route the wiring for the switches.


After pulling the switch wiring harnesses from the rear seats, they were attached to the back of the cigarette console plate.


The finished result for the rear seats.


The E38 has really good carpet with thick insulating padding underneath that makes it really stiff. Once lifted up, a stiff wire was used to thread a piece of string across to the console, which was then used to pull through the wiring for the switches from the rear seats.


And, in case you've ever wondered, this is what your rear-seat cupholder looks like when removed. Mine wasn't opening, but it was easily fixed after a good cleaning.

To recap, here are the steps:

The main steps are:
1. Remove the chair from the car.
2. Remove the plastic sides and buttons from the seat.
3. Remove the metal assembly (the tracks and motors) from the bottom of the chair.
4. Take off the leather from the seat bottom.
5. Install the new foam cushion (I only did it for the driver's seat).
6. Install the heating element on the seat bottom. I actually attached it to the underside of the leather for the seat bottom due to the way the cables needed to sit.
7. Re-attach the leather to the seat bottom.
8. Remove the plastic trim from the seat back.
9. Take off the leather from the seat back.
10. Install the heating element in the seat back by sticking it to the rubberized horsehair pad in the seat.
11. Re-attach the leather to the seat back.
12. Re-assemble the seat and install it back into the car.

For the front seat, raise the seat to its highest position and lower the headrest. You have to remove the plastic covers on the tracks, then remove the four bolts that attach the seat to the floor. Tilt the seat toward the back so that you can disconnect the cables underneath. Finally, unbolt the seatbelt from the seat at the back of the chair beside the door. The entire seat can then be lifted (its heavy) out of the car.

Once removed from the car, remove the headrest by pushing up until it slides out. You have to push fairly hard to get it out. Remove the plastic side covers on either side of the seat bottom. There is a single screw at the front in a large hole and several plastic rivets that pop out along the bottom. Disconnect the wires connecting to the chair-position control buttons on the plastic housing.

You could probably work on the seat leather without removing the tracks on the bottom side, but its a lot easier without them so I recommend that you go ahead and remove them. To do that, unbolt the tracks from the chair frame. You'll need to disconnect a few wires in the process (and the air tube for the lumbar bladders), so use some masking tape to label the connections before disconnecting them.

To remove the leather, pry up the little metal tongs all along the side of the chair frame, then unhook the leather from those them. Turn the seat over and remove the long metal rods from the seams in the seat cushion (they pass through channels in the lining attached to the back of the leather). These rods are what keeps the leather tight against the seat and prevent it from moving around when you sit. Use a pair of pliars to remove the hog rings (the metal rings that looped around the metal rods to secure them to more metal in the seat cushion).

Affix the heating elements (see earlier pictures) then re-attach the leather by inserting the metal rods back into the lining of the leather. Use a hog-ring tool (or pliars) to connect the rods back to the seat cushions. Upholstery tools really help with this process (see earlier pictures). When that's done, turn the seat back over and start pulling the edges of the leather back over those metal tongs that you pulled up during the first step. When they're all in place, take a hammer and bend the tongs back down to keep the leather permanently in place. Repeat the process for the seat back.

The rear seats are easier to remove. The bench is removed by simply pulling up strongly on the front edge and lifting it out. The seat back is actually three pieces, one for the center and one each for the left and right sides. Start by removing the headrests by pulling strongly up. Then unscrew a bolt along the bottom near the seatbelt receptacle. Push up on the seat to release it from several clips in the back. Once away from the frame, you'll have to remove the seatbelt which passes through it by unbolting the seatbelt connection at the bottom of the seat bench, then pass the seatbelt up through the plastic housing at the top of the seat, which pops off and has a slit cut into it so that you can free it from the seatbelt.

I hope that helps. I'm writing this at the wee hours of the morning and am getting tired, so I've probably left out some small detail, but its really not that complicated -- just timeconsuming.

The seat heating kit is made by Check Corporation and is available through IPD, USA.

www.e38.org has links for everything about your BMW 7-series automobile

• 4-Seat heating retrofit project: rear seat pics (pic) (url) - DavidC 2003-12-27 23:43:52 (28389 views)