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Subject: I have warm buns again!! Author: visionman : member since August, 2004 : 18 posts Posted on: 2005-12-14 23:16:22

Well, I know it doesn't get as cold here in Seattle as you in the rest of the north country experience, but my seat heater bottom failed and I was freezing!!

I had the same thing happen in my previous 1990 750il, and the problem was a broken wire. I fixed that one, so I decided to tackle the 1997 version....

The seat come out very easily, just Six bolts and one big connector. Once I had the thing on my workbench, I removed the plastic trim and the seat switches. If you look underneath the seat, the leather is held on with triangular "tabs" that the leather is pierced with. All you have to do to remove the skin is to bend the tabs slightly and then stretch the leather up over the tabs. There must be 20 to 30 of these tabs.

There is one additional thing to remove. The skins have wire sewn into them that fit into seams molded into the foam. You have to use a wire cutter to snip the metal rings that hold these wires to the foam. Don't worry about saving these rings, you will replace them with zip ties.

Once you get the seat skin off (don't forget to take out the seat heater wire and connector) lay it out on your workbench, skin side down. There is a thick fabric heater insulation blanket over the seat heater wire; cut this fabric on three sides to expose the coils. Cut close to the seams -- you don't want to cut either the heater wires or the leather!!

Fold the insulation layer away, and you will see the heater wires. In both the cases I have fixed, the place that the wire had broken was obvious -- look for the burn mark under the coils. In this case the wire had broken at one of the junctions between the heater wire and some heavier conection wire. I simply cut the heater wire back some and re-soldered the wire to the connection piece.

I checked the continuity of the circuit at the connector to make sure I had found the problem. The impedance of the wire circuit is about .5 ohms.

I put some duct tape over the edges of the insulation blanket that I had cut -- Probably overkill. I re-attached the wire seams with zip ties instead of wire rings -- much easier. The skin went right back over the triangular tabs in the same holes they came out of.

Bolted back in the car, plugged in, and my buns are again warm!! Bliss!

Good luck,
Grant Bower
1997 750il

• I have warm buns again!! - visionman 2005-12-14 23:16:22 (8628 views)
  • Thanks for the post, my 95 is suffering from the same thing. - dragnet 2005-12-15 00:57:46 (451 views)