This article is one in a series that have been released in conjunction with Wayne's new book, 101 Performance Projects for Your BMW 3 Series. The book contains 272 pages of full color projects detailing everything from performance mods to timing the camshafts. With more than 650+ full-color glossy photos accompanying extensive step-by-step procedures, this book is required reading in any 3 Series owner's collection. The book was released in August 2006, and is available for ordering now. See The Official Book Website for more details. Surprisingly, seats present some of the most complicated components on any car. When you start adding bells and whistles to them (like heaters, occupancy sensors, power motors, and air bag sensors), you end up with a complicated device that gets a lot of use and often needs some attention. This project covers three basic repair procedures involving the E36 power seats: seatbelt receptacle replacement, seat occupancy sensor replacement, and power seat switch replacement.

The first step is to remove the front seat, which is a pretty easy task. Unbolt the seat from the chassis floor according to Photo 1. Then disconnect any electrical connections that may be located underneath the seat (Photo 2). Because each seat weighs between 60 and 80 pounds, I suggest that you have a helper assist you in lifting and carrying the seat from your car. You'd hate to lose your balance while lifting and bang your seat against the side of your car. With the seat removed, you will have relatively easy access to the remainder of the seat components. The belt buckle receptacle can easily be replaced once the seat is removed from the car (see Photo 1). The electrical switch inside this receptacle often fails, resulting in air bag warning lamp error messages (see Project 83). Replacement is as simple as unbolting the old unit, attaching the new unit, and running the wire harness through the seat. The passenger seat occupancy sensor is used to tell the air bag computer whether or not there is a person sitting in the passenger seat.

This avoids a potentially costly deployment of the passenger-side air bag if there isn't anyone sitting there. This sensor gets lots of use and is responsible for a significant portion of air bag lamp faults. Once you have determined that this sensor is the cause of the problem, replacement is fairly straightforward and costs about $85.Pet For Adoption In Sabah To access the sensor, you need to remove the lower seat pad. Car Rental Mccook NeThis pad is attached at four points, sometimes with screws and sometimes with plastic clips (see Photo 2 for removal instructions). Igt Warehouse SaleWith the pad removed, the sensor becomes visible. It is simply tacked down to the lower seat cup by double-sided tape that comes pre-attached to the sensor. To replace the sensor, simply pull off the old one and stick on the new one.

Reroute the wire harness for the sensor underneath the seat. Before buttoning up the seat completely, I would carefully carry it over to your car and plug it into the wire harness to see if the air bag computer still gives an error message (for this, you will need an air bag reset/code reading tool like the one described in Project 83). It's better to find out now if there is a problem with the assembly than after you have reinstalled the seat. A note of caution: Do not put the key into the ignition with the seat removed if you are not having trouble with your air bag. If you put the key into the ignition and turn it on with the seat disconnected, the air bag computer will register a fault, and the light will go on. Then you will not be able to reset the light without a code reset tool. The power seat switch assembly is a complicated electrical piece that often fails after many years of use. To replace the switch, simply remove the bolts that attach the lower seat cup to the assembly (Photo 3).

Then flip the seat around and remove the switch retainer from the seat assembly (Photo 4). Finally, the switch should pop out of its connector, once the retaining ring is released (Photo 5). You may want to check the seat springs before you reinstall. Coating them with some light oil will prevent them from squeaking in the future. Reassembly of the seat is indeed the opposite of assembly. The seats weigh roughly 70 pounds, so you might want to have a helper assist you with the final installation process. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.

Removing the seat is easy. Simply slide the seat all the way back, and remove the nut that attaches the seat to the floor (under the black plastic cap). Next, slide the seat all the way forward, and remove the bolts at the rear. The seat should then be able to be tipped upward so you can disconnect any of the electrical connections that attach to it from underneath. With the seat unbolted from the car, simply disconnect the wire harnesses from underneath. Your particular seat may have a few more or a few less harnesses than the one shown here. The green arrow shows the power connector; the yellow arrow shows the seatbelt receptacle sensor plug; the orange arrow shows the air bag occupancy sensor plug. The first thing to do when you get your seat onto your workbench is disable the seatbelt pyrotechnic receptacle. This seatbelt device activates in conjunction with the air bags in an accident, and it can accidentally go off while you're working on it. Using a small screwdriver, turn the small green lever (yellow arrow) until the indicator on the side of the unit turns to red (blue arrow).

In this photo, you can also see the bolts that attach this seatbelt assembly to the seat (use a Torx driver). If your assembly has activated accidentally, you can easily replace it now. Remember to turn the seatbelt mechanism back on when you install the seat back into the car. On the bottom of the seat, you will see the complicated mess that controls all of the seat functions. In order to gain access to the electric seat switches or the passenger seat occupancy sensor, you need to first remove the top cushion. The cushion is held on at four points--on some cars, using four plastic clips; on others, a combination of screws and clips. This particular seat has both. The plastic clips need to be clipped off (blue arrows), and the screws that hold the front of the pad to the seat need to be removed using a Torx driver (yellow arrows). With the top cushion removed, you can now see the seat occupancy sensor in place. This sensor is a thin, complicated-looking film attached to the top of the seat cup using double-sided tape.

A brand-new replacement sensor is shown in the inset photo. Replacement is as easy as peeling back the old sensor and attaching the new one. Also shown here are the Torx bolts that attach the seat cup to the rest of the seat assembly (green arrows). Removal of these bolts is necessary in order to gain access to replace the electrical seat switches. Shown here are the electrical seat switches. With the lower seat cup removed from the rest of the frame, you can remove the three or four small Torx screws that attach the seat switch retainer to the seat frame. Once this retainer is free, you can easily remove the switch. Begin by prying off the switch knobs with a small screwdriver. Then remove the one Phillips-head screw that attaches the switch to the retainer (red arrow). The switch should then be able to be snapped out of the plastic retainer. This photo shows the electric seat switch assembly. Remove it from the seat wire harness by pulling back on both ends of the connector retainer (yellow arrows).