| Originally posted by lulul@Jan 21 2005, 01:42 PM |
I just got the car couple of weeks ago 92 325i and the heated seats are not working.
When i press the heated seats buttoon, it would light up but won't hold just maybe for 5 seconds and then the light turns off. The same for the passenger seat.
hey i feel your pain, i had the same toruble on my 93 325i and i only fixed because the winter last year in ny was around 20F druing december..
this is what you have to do...
first of, go under the seat.. youll see a bucnh of wire plugs under there. one for the electric power for the seats and two other for the heating element inside the seat..
to ensure that it is receiving power you have to do the following..
get a multimeter, set it on the voltage measurment/ 12 v dc/
under the seat, the white electrical plug brings +12v and ground strait form the battery for the electric motor on the seat. then you-ll see two black one. that one is the power input for the heater element on the seat. If im not worng, it will have 2 red wires, but each has markings to identify wich one is wihc,, this is not inportant..
well unplug the plugs from the seat. then with the voltmeter, check if you are getting power on the black plugh that comes from the car. make sure the key is on and that you have selectec hot on the swicth. it should be giving someting around 12v on the plug..if no power from the cars plug, open the plasctic cover above the pedals, us spec. there are some relays on the side there, you will be looking for the relay called, unloader relay terminal 15. just look at the atached picture of the BMW electrical diagram. This relay send the power from the fuses, to the seat control, and from there it goes to the seats. Also this sytem uses 2 fuses, so make sure both work. check the relay to ensure is working.
and if relay works and you still not getting power from the car to the seat, then is most likely the siwcht.
but i will be onest here, it is very unlikely that the relay or swicht went to the graveyard.
so keep reading..
after many years, the heating elements inside the chair brakes, it uses thin filaments, they brake, or burn out..
to test to see wether the pad is working do the following.
under the seat, using the black plugs, this time the ones that are coming from the seat.. measure to see if there is electrical resistance.. using the multimeter set on resistance, see if the circuit is being completed.. the way the heater works is that is a thing electrical wire, this wire has and internal resistance that when power goes trought it it generates heat. like on a electrical oven resistor. but smaller.
so if some wire got broken, it will not complete the loop and you wont be able to get any read out.. also sometimes the wire is about to break, so you might measure and get a reading, to ensure is not triking you, keep pressing the seat, so it will simulate as if you where seated..
if you determine the wire is broken, no resistance on the heating element, cant read nothing on the multimeter.. gthen the anoying part begin here..
first go to the dealer, buy the two heating elements, one for the bottom one for the top. and 4 bottom cushion clips, this are plastic clips that brake when you need to pull the cushion out..note here, even if only one of the elements is broken, just replace the whole thing, because youll take the seat apart..
here it starts,
get the seat out of the car. before pulling it out, it is safer that you move the belt tensioner onto the unloaded position, follow this on the bentley manual..
then get on the bottom cushion and pull from one of the corners out as hard as you can, the clips with let go and so the cusion is loose.
then after pulling ou you see the electrical plug comiig form the rear of it to power the heating element inside, that is where you need to go.. from the sides youll see that the leather is help in place by going over plastic edges, undo that, roll the leather up, then you see, where the leather lines are there are several metal c clips that hold the leather part to a metal inside the molded foam, get a pair of pliers and undo all of those C clips. its anoying.. but easily duable, once out, youll see the old pad, and much likely a burnt mark, that is where it burns at.
well get it out, then put the new one in, a little note for this. the new pad will have wirtten on it wich direction it has to go., just follow that. then reasemble is reverse removal of the leather, once the bottom one is done, go for the back rest.
in order to get the backrest, you need to plug the seat to a 12v supply, because you will have to lower the bacrest as much as possible since there are some of the C clips going from the bottom of it to the plastic bottom part of the seat. after taking those out, you have to get the headrest out, put it all the way out, it will stop, there is a lock to it. to undo this, undernead the headrest there is a plastic grill on the top of the backrest, pull it up, then youll see where the headrest goes into and little metal pins keeping it from getting out, using screwdriver or something like it undo the pins and take the headrest out.
then under the grill, youll see 2 torx screws, undo them, then the whole backrest will slide upwards and out form the seat metal frame.. this is a great time to properly clean and lubricate all the power seat system, rail aetc..
with the backrest cusion in front of you, turn it backyards and face the rear hard part up, on the bottom of it you see where there are come C clips on the side that keep the leather cover in place, undo it, and then start pulling the leather out, youll understand what im saying, once you get the clip out, just keep following the leather to take it out of its groove. then once the sides are removed, you find the same C clips and metal things inside, undo them put new pad in and reassemble everything.
this procedure might look complicated,m but is not, and at the end youll even get the heat going again...
keep us posted