hi [QUOTE=tazio;7105351]Here are tips for avoiding fault codes and warning lights when putting in different front seats. Most of these have already been posted and are known, but I think a couple of them are new - the correct resistance of airbags in front seats, and how to avoid fault codes for the passenger weight sensor system.

I'll describe in two parts, it depends on whether you replace your seats with other OEM Lancer seats, or with aftermarket seats. Disconnect battery before starting any of this.

INSTALLING DIFFERENT OEM FRONT SEATS
Driver's seat should be "plug and play", no issues. Problem on passenger side is weight sensors and related ECU module under the seat, these are uniquely coded to the central SRS ECU in the vehicle. Here's how I avoided this fault code. Take out the complete original passenger seat. The sliders and the seat float and mount on 4 weight sensors, these shiny weight sensors are also attached to what I'll call the bottom bracket. Under each weight sensor, there are two matching nuts. Undo the 8 nuts, then lift seat off the bottom bracket. Attached is a photo of one of the weight sensors, showing one of the eight nuts to undo. Also a photo of the bottom bracket, with the 4 weight sensors and related ECU module still on it. Swap this bottom bracket onto your new OEM seat and install in car. Central SRS ECU sees the original weight sensors and ECU module, so there is no fault code.

INSTALLING AFTERMARKET FRONT SEATS
A couple more issues to deal with. First, to deal with the passenger side weight sensors, keep the bottom bracket described above. You'll need to fabricate an adapter on which to put your new seat rails or new seat, so that the new seat mounts onto the original weight sensors on the original bottom bracket. Fabricating the adapter with flat metal bars is the best way to go.

Also, if you ditch the 3pt belts and only use harnesses, you will have to deal with the belt buckle sensors in the female part of the buckle. I got a couple of "dummy" female buckles with the male inserted in them, secured under each seat, and plugged electric leads to harnesses. Can source these from a junkyard if you don't want to sacrifice your originals. Central SRS ECU now sees both front seat belts as on all the time. There may be an easier way to do this, maybe use resistors instead?

Driver's seat has another sensor - the seat slide position sensor, it controls how the steering wheel airbag deploys - one stage or two stages. Photo of the sensor is attached. Go get one from a junk yard, or keep the one from the OEM seat you removed. Secure to the floor or under your new seat, plug lead into harness. This sensor normally works thus: with the seat slid forward of a certain point, a steel prong or plate covers the sensor and the SRS deploys the steering wheel airbag one stage, based on driver being close to the steering wheel. If the seat is moved backward of that point, the sensor is not covered by the plate, SRS deploys stage two of the airbag, based on driver being further away. So when you secure the loose sensor under the seat, you can choose to have the business side of the sensor either facing or not facing a piece of steel (e.g. your new seat bracket), to choose whether you want stage one or stage two steering wheel airbag deployment. The business side of the sensor is the side opposite the one with the writing on it.

Last but not least - if you put in aftermarket front seats, you will get SRS fault codes for not having the airbags in the seats. I measured the resistance of the airbag in the front seats, it is 2 ohms. Went down to Radio Shack, they had no 2 ohm resistors, but I got two 5-packs of 1/2 watt 10 ohm resistors, one 5-pack for each seat. Connect five 10 ohms in parallel, you get 2 ohms. I connected these to the yellow connectors in the harness coming out of the flow. Central SRS ECU sees two air bags still there.

I think that's everything that enables front seat swaps with no fault codes. Much of this was already known, maybe all of it, I thought it might help to put everything down in one place. But what I had not found on the list when I first looked was the resistance of the airbags in the seats, and how to avoid the passenger weight sensor fault codes.

Now the disclaimer - this all worked for me on my 2008 Evo, but I can't