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Thread: Repair of seat heating mat

  1. #1
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3

    Repair of seat heating mat

    Besides other faults this is quite common:
    Failure of the seat heating is often caused by a broken heater wire on the main power supply line which leads thru the mat .The heating wires are soldered to it and break directly at this point.

    Repair:Remove the seat cover from the foam cushion.To find the broken connection start with the following work in the middle of the seat, where the broken connection is often found.Turn seat cover and use a cutter on the material under the leather and the inserted felt material on 3 sides approx. 1cm away from the end. Carefully cut from the seam (be careful to not damage the seat cover).

    Now fold the cut pieces and you can see at the heating mat with the heating wires and power connections that are on the white mat recognizable as yellow spots.
    The yellowish stain will show black burn marks, this is the defective connection. Scrape with a sharp knife the surface at this terminal to expose the heating wire and solder the wire again and put a piece of leather as a protection under it.
    Now test with a multimeter the heating mat for continuity. If everything is ok, sew the cut felt pieces together, it needs not be beautiful but just has to hold pieces together.

    Seat skin removal, http://bmwe32.masscom.net/sean750/Se...atSwapping.htm

    Here some pics where a new seat heating mats will be installed, so you see the felt mats etc http://www.7-forum.com/forum/24/sitz...bau-26997.html

    Anybody installed a carbon mat instead of the old seat heating mat with wires?
    Any recommendable supplier? Here some pics from the German 7-forum http://www.7-forum.com/forum/24/sitz...al-123716.html

    Be reminded that the seat heater only works, when the seat belt is fastened, I once read.
    Shogun tricks and tips for the E32 series are HERE!

  2. #2
    Join Date
    Mar 2007
    Location
    Loveland, Colorado USA
    Posts
    369
    My Cars
    1993 740i
    I have had good luck with this repair on several seat heading pads on my kids' E36's. The heating wire itself is of very small diameter and is tough to solder, no points for making this a pretty solder joint, just make sure it's solid.

    BMW seats covers are relatively easy to remove and replace because of the removable hard backs on the back rest. Don't let the hog rings intimidate you, the first 3 will suck and then it gets a lot easier once you find the technique!
    '93 740i - Mine
    '13 Range Rover Sport - Hers
    '08 Land Rover LR2 - Hers
    '96 328i - Son's
    '97 328ic - Daughter's
    '87 944 Turbo - Mistress
    '74 Alfa Romeo Spider - Italian Mistress
    Northern Colorado, USA


  3. #3
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    2 of the above links are no longer working due to server probs on the German 7-forum, here new
    http://www.7-forum.com/forum/showthr...eren+neueinbau
    http://www.7-forum.com/forum/showthr...rbon+universal

    Preparing to repair my driver seat mat in spring when it will be warmer.

    Here a brief google translation from a German E32 forum:
    Repair seat heating without having to go to the repair shop
    To all those who have problems with broken heating wires of the seat heater in leather E32. You will need repair heater mat BMW part no. 64 11 8 391 234.
    - Remove the plastic covers from the sides of the seat.
    - Bend the retaining clips for the leather and unhook the fastening clips under the leather
    - Carefully fold the leather towards the back.
    - Cut the sewn-up fleece with scissors in each of the three sewn-in fields left and right along the edge
    - Insert the three fields of the heating mat between the old heating mat and the leather and make sure that everything is flat and without wrinkles.
    - fold over the ends that are now overlapping
    - finally remove the adhesive film from the heating mat and glue it to the fleece.
    - The return line runs over the tension wires, it is better under the tensioning springs in which one cuts the fabric in which the tension wire runs, a piece of tile still under it, so it can come with the wires to no short circuit and with needle and thread the Fix the wire again
    - Assemble now and look forward to the warm seat.
    -----------
    Sitzheizung - Heizmatte reparieren ! http://www.7-forum.com/forum/showthr...ht=sitzheizung

    Ausfall der Sitzheizung liegt oft an einem abgebrochenen Heizdraht an der Hauptstromversorgungsleitung die durch die Heizmatte führt. Die Heizdrähte sind daran angelötet und brechen direkt an dieser Stelle ab.
    So kann man diese Reparieren :
    - den Sitzbezug vom Schaumstoff abbauen
    - um den defekten Anschluss zu finden beginnt man mit der folgenden Arbeit im mittleren Sitzfeld, da dort häufig der defekt Anschluss zu finden ist
    - den Sitzbezug umdrehen und mit scharfen Messer (Cutter) den unteren Stoff und den eingelegten Filz an drei Seiten ca. 1cm von der Naht entfernt vorsichtig aufschneiden (aufpassen das man nicht die Sitzbezug verletzt)
    - nun das eingeschnittene Stück umklappen und man sieht die Heizmatte mit den Heizdrähten und den Stromverbindungen die auf der weissen Heizmatte die als gelbliche FLecken erkennbar sind.
    -- der gelbliche Fleck der einen schwarzen Brandfleck aufweisst ist der defekte Anschluss
    - mit einem scharfen Messer die Oberfläche an diesem Anschluß durch schaben freilegen, den Heizdraht ein Stück abisolieren und erneut verlöten und ein Stück Leder als Druckschutz darunter legen
    - mit Messgerät nun die Heizmattte auf Durchgang prüfen
    - alles ok, dann das oder die aufgeschnittenen Felder mit Stopfgarn zusammen nähen ,das muss nicht schön sein sondern nur die Sache etwas halt geben.
    - nun zusammen bauen und sich auf gespartes Geld und warmen Sitz freuen.

    Seat heating - repair the heating mat!
    Failure of the seat heater is often due to a broken heating wire on the main power supply line leading through the heating mat. The heating wires are soldered to it and break off directly at this point.
    So you can fix this:
    - remove the seat cover from the foam
    - To find the defective connection you start with the following work in the middle seat field, as there is often the defective connection to be found
    - Turn the seat cover over and carefully cut the lower fabric and the felt on three sides about 1cm away from the seam with sharp knives (Cutter) (take care not to damage the seat cover)
    - Now fold over the cut piece and you see the heating mat with the heating wires and the power connections on the white heating mat which are recognizable as yellowish flickers.
    - the yellowish stain that has a black burn mark is the broken connection
    - Scrape the surface of this connection with a sharp knife, strip the heating wire a little bit and solder it again, and put a piece of leather under it as pressure protection
    - Now check the heating mat for continuity with the measuring device
    - if all ok, then sew the cut or the fields together with stuffing yarn, that does not have to be nice, but just to hold the pieces together.
    - Now assemble it again and look forward to saving money and a warm seat.

    Seat Heating Retrofit instructions, EBA – 01 29 9 789 415 ,BMW Installation Instructions https://bmweba.com/eba-01-29-9-789-415/

    More E32 EBA: BMW EBA ONLINE - INSTALLATION INSTRUCTIONS https://bmweba.com/tag/e32/
    Last edited by shogun; 01-08-2018 at 09:24 AM.
    Shogun tricks and tips for the E32 series are HERE!

  4. #4
    Join Date
    Jan 2005
    Location
    Japan
    Posts
    54,654
    My Cars
    11/88 E32 750iL+98 E36M3
    Installed on driver seat in the summer a carbon mat I bought from Ebay, 2 mats made in China. Cost incl. shipping was only abt. $20. Installation based on this German instruction http://www.7-forum.com/forum/showthr...rbon+universal
    The universal mats came with non-BMW plugs of course, so we cut off the original wires and plugs from the original mat and cut off the universal plug and added the BMW plug with pigtail, so all looks original.
    The original seat heater mat we left where it was, as the old thin vlies material was very brittle.
    As now is winter time, I could test the carbon mat. Heats well even in step 1, no problem at all. My 11/88 750 has the old style heater mat switches which can only switch low-off-high, not the newer version with the electronics under the switches.
    61311374221 up to 09/1990
    61311390888 from 09/1990
    these switches are not interchangeable.

    During the repair process as usuall some of the connectors broke, for example the plug which goes into the seat heater switch from below, and some plugs of the seat and mirror memory module under the seat. Luckily I had all of them on stock, including some reare ones which are NLA. For the SMM module you need flwg plugs:
    61131378441 weiss/white
    61131378129 schwarz/black

    above are still available.

    no longer available are the plugs:
    61 13 1 378 442 (blau) blue
    61 13 1 378 443 (gelb) yellow
    61 13 1 378 444 (gruen) green
    61 13 1 378 445 (braun) brown

    Differences are the colours and the direction of the triangle position pin hole. All show in different directions so that the plugs cannot be plugged into the wrong port. As we have only white and black available now, use a 7mm drill and drill the triangle to a round 7mm hole, then the plugs fit in all ports. But better mark them to be not confused.
    Shogun tricks and tips for the E32 series are HERE!

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